Curent Charge and PD

2 A rechargeable cell carries the marking 150 milliamp hours2 What charge does this correspond to?

• 9 C
• 540 C
• 9000 C
• 540 000 C

3 The current in a bulb is 250mA. How much charge flows in 3 minutes

• 0.75C
• 45C
• 750C
• 45000C

4 A rechargeable cell stores a maximum energy of 4200 J. The cell has an e.m.f. of 1.5 V and after 2.0 hours use the cell is completely discharged. Assuming the e.m.f. stays constant, the charge passing through the cell during this time i

• 1400C
• 2800C
• 5600C
• 6300C

5 An electric motor with potential difference V and current I lifts a mass m through a height h in time t at a steady speed v. The efficiency of the motor is given by

• (.5mv^2)/Vit
• VI/mg
• Vit/mv
• mgh/Vit

6 A current of 0.2 A flows through a lamp for 3 hours. The total charge passing through the lamp in this time is

• 21600C
• 600C
• 36C
• 0.6C

11 A 100 W lamp connected to the 230 V mains is replaced by a lamp which has twice the resistance. The power of the new lamp is

• 25W
• 50W
• 200W
• 400W

13 During a thunderstorm, a flash of lightning resulted in 600000 C of charge flowing in a lightning conductor in a time of 40 ms. The current in the conductor was

• 1.5x10^4A
• 2.4x10^4A
• 1.5x10^7A
• 2.4 x10^7A

14 The amount of electrical energy transferred when a charge of 8 mC moves through a potential difference of 12 V is

• 1500 J
• 96J
• 9.6x10^-2J
• 6.7x10^-4J

17 A child’s toy is operated by a small motor. The potential difference across the motor is 6.0V and the current in it is 0.20A. The energy used by the motor in 120 s is

• 2.40J
• 60.0J
• 144J
• 3600J

20 Which of the following SI units is equivalent to the volt?

• ampere per ohm
• coulomb per second
• joule per coulomb
• joule per second