AksharaInternationalSchoolAshok Nagar, Vijayawada– 07
Question Bank
Light:
01.Define focal length and radius of curvature for a spherical mirror and give the relation between them.
02.What are real and virtual images?
03.What is a spherical mirror? Distinguish between a concave mirror and a convex mirror.
04.Define the principal focus of a concave mirror. Out of convex mirror and concave mirror, whose focus is situated behind the mirror?
05.Where should an object be placed in front of the concave mirror so as to obtain its magnified erect image?
06.What is the angle of incidence, when a ray of light falls on the spherical mirror from the centre of curvature? Can we obtain the image of an object formed by convex mirror on a screen? If not, why?
07.How can one ascertain without touching, whether a given mirror is plane, convex or concave?
08.An object is placed in front of a concave mirror between its focus and centre of curvature. Show with the help of a ray diagram, the position, size and nature of the image formed.
09.If an object is placed at a distance of 8 cm from a concave mirror of focal length 10 cm, discuss the nature of the image formed by drawing the ray diagram.
10.Give at least three uses of a concave mirror.
11.An object 2.5 cm tall is placed at a distance of 15cm from a concave mirror of focal length 10 cm. By means of an accurate ray-diagram, determine the position, size and nature of the image formed.
12.Write the sign convention used in optics.
13.Which type of mirror has: (i) positive focal length? (ii) negative focal length?
14.All the distances are measured from the ______of a spherical mirror.
15.At what distance from a concave mirror of focal length 10 cm should an object be placed, so that its image is formed 20 cm from the mirror?
16.If the magnification of a body of size 1m is 2, what is the size of the image?
17.State the relation between object distance, image distance and focal length of a mirror.
18.What is the ratio of the height of an image to the height of the object known as?
19.Define linear magnification produced by a mirror.
20.Which mirror has a wider field of view?
21.Which type of mirror is used in vehicles to see the traffic on the rear side?
22.Why does a driver prefer to use a convex mirror as a back view mirror in an automobile?
23.Draw a ray diagram to show the formation of image in a convex mirror. What happens to the image when the object is moved away from the mirror?
24.An arrow 2.5 cm high is placed at a distance of 25 cm from a diverging mirror of focal length 20 cm. Find the nature, position and size of the image formed.
25.What is refraction?
26.What are the laws of refraction?
27.Can absolute refractive index of a medium be less than unity?
28.Can relative refractive index of a medium w.r.t. another be less than unity?
29.Define the terms ‘critical angle’ and ‘total internal reflection’.
30.What type of lens is an air bubble inside water?
31.What are the uses of putting two lenses in contact with each other?
32.Define refractive index of a material. Distinguish between the terms absolute and relative refractive index of a medium. How are they related?
33.Give an expression for refractive index in terms of velocities of light.
34.Refractive index of glass is 1.5. Find the speed of light in glass, if its speed in air is 3x108ms-1.
35.What is a lens? Distinguish between a convex and a concave lens?
36.A point inside the lens through which the light passes undeviated is called __.
37.Which of the two is a diverging lens: convex or concave?
38.State whether a concave lens has a virtual focus or real focus.
39.Draw a ray diagram to show the formation of a real magnified image by a convex lens.
40.Where should an object be placed in order to use a convex lens as a magnifying glass?
41.For what position of an object, a real, diminished image is formed by a convex lens?
42.In which physical quantity is the power of a lens measured?
43.The focal length of a convex lens is 25 cm. What is its power?
44.The power of a lens is -2D. What is its focal length?
45.What do you understand by the power of a lens? Define its unit.
46.State the Cartesian sign convention for lenses.
47.How is power of a lens related to focal length?
48.Which type of lens has a (i) negative power? And (ii) positive power?
49.What is the difference between the mirror formula and the lens formula?
50.A convex lens produces an inverted image magnified three times of an object placed at a distance of 15 cm from it. Calculate (i) focal length of the lens and (ii) power of the lens.
51.An object 4 cm high is placed at a distance of 10cm from a convex lens of focal length 20 cm. Find the position, nature and size of the image.
52.Show by drawing a ray-diagram that the image of an object formed by a concave lens is virtual, erect and diminished.
53.If the image formed by a lens is always diminished and erect, what is the nature of the lens?
54.An object of height 4 cm is placed at a distance of 15 cm in front of a concave lens of power -10 dioptres. Find the size of the image.
Questions From Previous Papers
55.Draw a ray diagram to show the i) Position and (ii) nature of the image formed when an object is placed between focus F and pole P of a concave mirror.
56.A 5.0 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 20 cm. The distance of the object from the lens is 30 cm. By calculation determine (i) the position, and (ii) the size of the image formed.
57.A ray of light is incident on a concave mirror as shown below
Redraw the above diagram after completing the path of the light ray after reflection from the mirror.
58.An object is placed at a distance of 12 cm in front of a concave mirror. It forms a real image four times larger than the object. Calculate the distance of the image from the mirror.
59.State the relation between object distance, image distance and focal length of a spherical mirror. A concave mirror of focal length 15 cm forms an image of an object kept at a distance of 10 cm from the mirror. Find the position, nature and size of the image formed by it.
60.Draw a labeled ray diagram to locate the image of an object formed by a convex lens of focal length 20 cm when the object is placed 30 cm away from the lens.
61.During its passage from one medium to another, when does a light ray change its path?
62.Define the term absolute refractive index of a medium?
63.With the help of a ray diagram explain the term ‘critical angle’.
64.For a ray of light going from a denser medium to air, what is the value of refractive index of the medium if the critical angle is equal to 450.
65.Where will the image be formed by a concave mirror when an object is placed between the pole and the focus point of the mirror?
66.With respect to air the refractive indices of water and benzene are 1.33 and 1.50 respectively. Calculate the refractive index of benzene with respect to water.
67.What are the values of (i) the angle of incidence, and (r) the angle of reflection for normal incidence on a plane mirror surface?
68.Light enters from air into a glass plate which has a refractive index of 1.50. Calculate the speed of light in glass. The speed of light in air is 3.0 x 108 ms-1.
69.A convex lens has a focal length of 25 cm. Calculate the distance of the object from the lens if the image is to be formed on the opposite side of the lens at a distance of 75 cm from the lens. What will be the nature of the image?
70.With the help of ray-diagrams show the phenomenon of total internal reflection of light and the concept of critical angle for a transparent medium.
71.A 5 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 20 cm. The distance of the object from the lens is 30 cm. Find the (i) position, (ii) nature and (iii) size of the image formed.
72.What is meant by ‘critical angle’ for a ray of light going from one medium into another?
73.What is the consequence of making angle of incidence of light, at an interface, greater than the critical angle?
74.Why does a cut diamond shine more than a glass piece with diamond cut?
75.What wilt be the focal length of a lens whose power is given as + 2.0 D?
76.An object 3 cm high is placed at a distance of 20 cm in front of a convex lens of focal length 12 cm. Find the position, nature and size of the image formed.
77.An object 3 cm high is placed at a distance of 9 cm in front of a concave mirror of focal length 18 cm. Find the position, nature and size of the image formed.
78.Find the position, nature and size of the image formed by a convex lens of focal length 12 cm of an object 3 cm high placed at a distance 20 cm from it.
79.Find the position, nature and size of the image of an object 3 cm high placed at a distance 9 cm from a concave mirror of focal length 18 cm.
80.If the magnification of a body of size 1m is 2, what is the size of the image?
ELECTRICITY
01.What do you understand by the term “potential difference”? What is the S.I. unit for it?
02.By what name is the unit joule/coulomb called?
03.Name the instrument which is used to measure potential difference.
04.Define Volt.
05.Calculate the work done in moving a charge of 4 coulomb from a point at 220 volts to another point at 230 volt.
06.Define electric current. Give its unit.
07.Define Ampere.
08.How voltmeter and Ammeter are connected in a circuit?
09.What is a voltmeter and what is an ammeter?
10.If the charge on an electron is 1.6 x 10-19 C, how many electrons should pass through a conductor in 1 second to constitute 1 ampere current?
11.What is Ohm’s law? Explain how it is used to define the unit of resistance.
12.Name the unit in which electrical resistance is measured.
13.What happens to the resistance as the conductor is made thinner?
14.Distinguish between conductors, resistors and insulators.
15.The potential difference between the terminals of an electric iron is 240V and the current is 5 A. What is the resistance of the electric iron?
16.Keeping the potential difference constant, the resistance of a circuit is doubled. By how much does the current change?
17.What are Ohmic and non-Ohmic conductors? What is the shape of the graph drawn between current and voltage in the above cases?
18.With the help of a diagram, derive the formula for the equivalent resistance of three resistances connected in series.
19.With the help of a diagram, derive the formula for the equivalent resistance of three resistances connected in parallel.
20.Give the law of combination of resistances in series.
21.Give the law of combination of resistances in series.
22.If n resistances of R ohm each are connected in parallel, what will be their total resistance?
23.If n resistances of R ohm each are connected in series, what will be their total resistance?
24.Two resistances when connected in parallel give resultant value of 2 ohm; when connected in series the value becomes 9 ohm. Calculate the value of each resistance.
25.In order to get the resultant resistance greater than the greatest of the given resistances how they will be connected?
26.In order to get the resultant resistance less than the least of the given resistances how they will be connected?
27.Define electric power. Write its S.I. unit.
28.How many joules are equal to 1 watt-hour?
29.Name the commercial unit of energy.
30.Define kilowatt-hour. Calculate the cost of operating a heater of 500W for 20 hours at the rate of 35 paise per unit.
31.Which has a greater resistance, a 100 watt bulb or a 60 watt bulb?
32.State whether an electric heater will consume more electrical energy or less energy per second when the length of its heating element is reduced. Give reasons for your answer.
33.A bulb is rated as 250V; 0.4A. Find its : (i) power and (ii) resistance.
34.State three factors on which the heat produced by an electric current depends.
35.Give two applications of heating effect of electric current.
36.A resistance of 25 Ohm is connected to a 12 V battery. Calculate the heat energy in joules generated per minute.
37.The current passing through a room heater has been halved. What will happen to the heat produced by it?
38.Give two reasons why different electrical appliances in a domestic circuit are connected in parallel.
39.What name is given to the device which automatically cuts off the electricity supply during short circuiting in household wiring?
40.Of what substances is the fuse wire made? Why?
Questions from Previous Papers
- What is the S.I. unit of electric potential ?
- An electric iron has a rating of 750 W, 220 V. Calculate current passing through it, and its resistance, when in use.
- (a) What is meant by ‘Electric Resistance’ of a conductor ?
(b) A wire of length L and resistance R is stretched so that its length is doubled and the area of cross-section is halved. How will its: resistance change? resistivity change?
- What is meant by the statement, “Potential difference between points A and B in an electric field is 1 volt.” ?
- An electric lamp is marked 100 W, 220 V. It is used for 5 hours daily. Calculate its resistance while glowing. Energy consumed in kWh per day.
- a) State Ohm’s Law.
b) Draw a schematic diagram of the circuit for studying Ohm’s Law.
- An electric heater is used on 220 V supply and takes a current of 3.4 A. Calculate (i) its power and (ii) its resistance, when it is in use.
- (a) Draw a schematic diagram of a circuit consisting of a battery of five 2 V cells, a 5 ohm resistor, a 10 ohm resistor and a 15 ohm resistor, and a plug key, all connected in series.
(b)Calculate the electric current passing through the above circuit when the key is closed.
- Draw a diagram to show how two resistors R1 and R2 are connected in series.
- In a circuit if the two resistors of 5 ohm and 10 ohm are connected in series, how does the current passing through the two resistors compare?
- A bulb is rated at 5.0 volt, 100m A. Calculate its power and resistance.
- There are two electric bulbs, marked 60 W; 220 V and marked 100 W; 220 V. Which one of the two has a higher resistance?
- In a household 5 tube lights of 40 W each are used for 5 hours and an electric press of 500 W for 4 hours every day. Calculate the total electrical energy consumed by the tube lights and press in a month of 30 days.
- Out of the two, a toaster of 1kW and an electric heater of 2 kW, which has a greater resistance?
- Name a metal which offers higher resistance to the passage of electricity than copper.
- Which has a higher resistance: a 50 W lamp bulb or a 25 W lamp bulb and how many times?
- A torch bulb is rated 2.5 V and 750 mA. Calculate (i) its power, (ii) its resistance and (iii) the energy consumed if this bulb is lighted for
four hours. - A wire of resistance 10 ohm is bent in the form of a closed circle. What is the effective resistance between the two points at the ends of any diameter of the circle?
- If a 24 V battery is connected to the arrangement of resistances given below, Calculate the total effective resistance of the circuitandthe total current flowing in the circuit.
- State the formula correlating the electric current flowing in a conductor and the voltage applied across it. Also show this relationship by drawing a diagram.What would be resistance of a conductor if the current flowing through it is 0.35 ampere when the potential difference across it 1.4 volt?
- An electric bulb draws a current of 0.2 A when the voltage is 220 volts. Calculate the amount of electric charge flowing through it in one hour.
- Three resistors are connected as shown in the figure. Through a resistor 5 ohm a current of one ampere is flowing: (a)what is the p.d. across AB and across AC?
(b) what is the current through the other two resistors?(c) what is the total resistance? - A bulb is rated at 200 V-100 W. What is its resistance? Five such bulbs burn for 4 hours. What is the electrical energy consumed? Calculate the cost if the rate is 50 paise per unit.
CHEMICAL REACTIONS AND EQUATIONS
01.What is meant by a chemical reaction? Give an example.
02.State the characteristics of chemical reactions.
03.Why should magnesium ribbon be cleaned before burning in air?
04.What is a chemical equation? Explain with the help of an example.
05.What are balanced and unbalanced chemical equations? Give examples.
06.Why should chemical equations be balanced?
07.What do you understand by exothermic and endothermic reactions? Explain with examples.
08.Aluminium burns in chlorine to form aluminium chloride, AlCl3. Write a balanced equation for this reaction.
09.Carbonmonoxide reacts with hydrogen under certain conditions to form methanol(CH3OH). Write a balanced chemical equation for this and state the conditions under which this reaction takes place.
10.What do you understand by combination reaction, decomposition reaction? Give examples.
11.What happens when silver chloride is exposed to sunlight? Write a chemical equation for this reaction. Also give one use of such a reaction.
12.Why are decomposition reactions called the opposite of combination reactions? Explain with equations of these reactions.
13.What is meant by a displacement reaction, double displacement reaction? Give examples.
14.What do you mean by precipitation reaction? Give an example.
15.Why does the colour of copper sulphate solution change when an iron nail is kept immersed in it?
16.Explain the following in terms of gain or loss of hydrogen with one example each: (a) oxidation (b) reduction
17.Explain the term ‘corrosion’ with an example.
18.Explain the term ‘rancidity’
19.What are anti-oxidants? Why are they added to fat and oil containing food?
20.Which chemical reaction is involved in the corrosion of iron?
Questions from Previous papers
21.Why potato chips manufacturers fill the packet of chips with nitrogen gas?
22.Identify the substance oxidised and reduced in the chemical reaction: Mn O2 + 4 HCl ——> Mn Cl2 + Cl2 + 2H2O
23.Can a displacement reaction be a redox reaction? Explain with example.
24.Give an example of an endothermic reaction.
25.Give an example of photochemical reactions.
26.State a reaction in which SO2 acts as an oxidising agent.
27.Write the chemical equation for the reaction of hot aluminium with steam.
28.A green layer is gradually formed on a copper plate left exposed to air for a week in a bathroom. What could this green substance be?
29.Write the chemical equation to represent the reaction taking place when copper oxide is heated in a stream of hydrogen.