Electricity Problem Sets

Electricity Problem Sets

1. Current

a)What is the current through a circuit with 122.5 coulombs passing through a light bulb in 1 minute?

b)How many coulombs pass through a 15 A circuit in 3.6 seconds?

c)How long does it take 17 coulombs to pass a point along a conducting wire in a 20 A circuit?

d)What is the current running through a circuit with 10 coulombs passing by a point in 5 seconds?

e)How many coulombs are passing through a 20 A circuit in 2 seconds?

f)How long does it take for 50 coulombs to pass a given point in a 10 A circuit?

2. Voltage

a)IF each coulomb in a circuit has 10 J of energy, what is the voltage?

b)How many coulombs are there if the energy in 6 V is 15 J?

c)If the potential difference is 50 V and there are 10 coulombs, how much energy does each coulomb have?

d)A battery converts 72 J of chemical energy into electrical energy. This places 12 C of negative charge at the negative terminal. What is the potential difference between the negative and positive terminals of the battery?

e)How much energy can an electric motor produce when it is plugged into a 110 V outlet with a total charge of 50 C passing through the motor?

f)Gasoline-powered generators change chemical energy (from gasoline) into electrical energy. If a generator produces 120 V with a charge of 60 C at the negative terminal, how many joules of energy are produced?

g)If the generator in question (c) burned enough gasoline to produce 28 800 J, what would the coulomb charge be at the negative terminal?

3. Resistance

a)A light bulb passes a current of 0.83 A when the potential difference across the bulb is 120 V. What is the electrical resistance of the bulb in ohms?

b)Only 2.5 x 10-3 A of current pass through a portable CD player. If the CD player is operated by a 9 V battery, what is the resistance within the circuit?

c)An automobile headlight has an average resistance of 24 Ω. Car batteries provide a potential difference of 12 V. What amount of current passes through the headlight?

d)What is the potential difference across an electric water heater element that has a resistance of 32 Ω when the current through it is 6.8 A?

e)In a portable radio, 0.5 A of current are flowing through a conductor that provides 18 Ω of resistance. What potential difference is provided by the battery?

f)A clothes dryer uses 220 V power source. The coils of the heater provide an average resistance of 12 Ω. What amount of current is flowing through the heating coils?

4. Power

a)A portable hair dryer plugged into a 110 V outlet has a current of 10 A flowing through it. What is the power rating of the hair dryer?

b)A CD player that was on for 1 hour used 360 000 J of electrical energy. What is its power in watts?

c)A gasoline-powered generator consumes 15 000 J of energy in 5 minutes. How much power did it produce in this time?

d)A washing machine has a power rating of 512 W. If one cycle lasts 30 min, how much energy does the machine use per cycle?

e)A light bulb draws 1.25 A of current from a 120 V gasoline-powered generator. If the generator runs for 10 minutes, how much energy will the lamp convert into heat and light? (Hint - Calculate power first)