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Worksheet: Energy Dissipation by Conductors

Q1:

A resistor has a resistance of Ω and dissipates electrical energy at a rate of 2.0 W.

What is the current through the resistor?

What is the voltage drop across the resistor?

Q2:

A heart defibrillator produces a current of 10.0 A in a patient’s torso for 5.00 ms in an attempt to restore a normal heartbeat. 500 J of energy was supplied by the defibrillator.

How much charge was passed through the patient?

  • A
  • B
  • C
  • D
  • E

What voltage was applied to the charge that passed through the patient?

What was the resistance of the path taken by the charge that passed through the patient?

Q3:

A resistor of an unknown resistance is placed in an insulated container filled with 0.75 kg of water. A voltage source is connected in series with the resistor producing a current of 1.2 A through the resistor that is maintained for 10.0 minutes, producing a water temperature increase of . Assume a value of for the specific heat capacity of water.

What is the resistance of the resistor?

What is the voltage supplied by the power supply?

Q4:

A physics student uses a 115.00-V immersion heater to heat 400.00 grams (almost two cups) of water for herbal tea. During the two minutes it takes the water to heat, the physics student becomes bored and decides to figure out the resistance of the heater. The student starts with the assumption that the water is initially at the temperature of the room and reaches . The specific heat of the water is . What is the resistance of the heater?

Q5:

A battery-operated car that has a mass of 750 kg is powered by a 12.0-V battery. The car accelerates from rest to 25.0 m/s, climbs a hill with a height of 200 m, and finally travels at a constant 25.0 m/s while exerting a force of 500 N for 3 600 seconds. How much charge does the car’s battery move through its electric motor?

  • A C
  • B C
  • C C
  • D C
  • E C

Q6:

A battery with an emf of 24.00 V delivers a constant current of 2.00 mA to an appliance.

How much work does the battery do in 180 seconds?

Q7:

A current of 25 A is drawn from a -V battery for 30 seconds. By how much is the chemical energy of the battery reduced?

Q8:

A 120-V immersion heater consists of a coil of wire that is placed in a cup to boil the water. The heater can boil one cup of water in 180.00 seconds. A student buys one to use in their dorm room, but they are worried that they will overload the circuit and trip the 15.00-A, 120-V circuit breaker, which supplies the dorm room. In the dorm room, there are four 100.00-W incandescent lamps and a -W space heater.

What is the power rating of the immersion heater?

What will be the total current in the circuit connecting the room if the immersion heater is turned on?

What will be the total current in the circuit connecting the room if the incandescent light bulbs are replaced with 18.00-W bulbs?

Q9:

A wave on a string is driven by a string vibrator, which oscillates at a frequency of 100.00 Hz and an amplitude of 1.00 cm. The string vibrator operates at a voltage of 12.00 V and a current of 0.200 A. The power consumed by the string vibrator is . Assume that the string vibrator is efficient at converting electrical energy into the energy associated with the vibrations of the string. The string is 3.00 m long, and is under a tension of 60.00 N. What is the linear mass density of the string?

  • A kg/m
  • B kg/m
  • C kg/m
  • D kg/m
  • E kg/m

Q10:

A lightning bolt strikes a tree, moving 20.0 C of charge through a potential difference of MV.

How much energy was dissipated by the lightning strike?

  • A J
  • B J
  • C J
  • D J
  • E J

Assume that all of the energy supplied to the charge in the lightning strike is converted to heat. The specific heat capacity of water is J/kg⋅C and the specific latent heat of vaporization of water is kJ/kg. What mass of water could be raised from to its boiling point and then boiled by this energy?

Q11:

A student uses a 100-W, 115-V radiant heater to heat his dorm room, between 6:00 pm and 7:00 am.

What current does the heater operate at?

How many electrons move through the heater?

  • A
  • B
  • C
  • D
  • E

What is the resistance of the heater?

How much heat was added to the dorm room?

  • A J
  • B J
  • C J
  • D J
  • E J

Q12:

A power plant that is located m from a town transmits electrical power through copper wires of cross-sectional area 42.40 mm2 and resistivity of Ω⋅m. The power is transmitted by a 100.0 A current. How much power is dissipated during transmission?

  • A W
  • B W
  • C W
  • D W
  • E W