Target: 10 Questions in 10 minutes

An IB Physics data booklet is helpful

 1. What is the resistance of an ideal voltmeter and an ideal ammeter?

2. A cell of negligible internal resistance and emf ε is connected to a load resistor of resistance R. What is the charge flowing round the circuit per second?

• A. ${ε R} $
• B. ${ε} \over{R}$
• C. ${ε^2 R} $
• D. ${ε^2} \over{R}$

3+4. The circuit below shows a potential divider circuit. The voltmeter has a near infinite resistance and has no effect on the circuit.

3. What is the reading on the voltmeter?

• A. 3 V
• B. 4 V
• C. 6 V
• D. 8 V

4. The voltmeter is replaced with a cheap voltmeter with a resistance of 100 kΩ . What is the new reading on the voltmeter?

• A. 3 V
• B. 4 V
• C. 6 V
• D. 8 V

5&6: Two copper cables P and Q are compared. Both cables are the same length.

5. Which of these correctly describes the resistivity and charge carrier density in the copper cables?

6. Rod P has a resistance of R. Rod Q has double the radius of rod P. What is the resistance of rod Q?

• A. ¼R
• B. ½R
• C. 2R
• D. 4R

7. Rod P is connected to a cell of EMF 3 V, and negligible internal resisitance. The energy lost as heat in the cable in a time t is given by:

• A. ${3 t} \over{R}$
• B. ${9 t} \over{R}$
• C. ${3} \over{Rt}$
• D. ${9} \over{Rt}$

8-10. A 2Ω resistor is connected to a cell of e.m.f. 12V and with significant internal resistance:

8. Which of these formulas for the circuit is correct?

• A. 12 = 2I + r
• B. 12 = 2I + 2r
• C. 12 = I(2 + r)
• D. 12 = 2(I + r)

9. The current I in the circuit is found to be 4 A . What is the reading on the voltmeter?

• A. 2 V
• B. 4 V
• C. 6 V
• D. 8 V

10. What is the value of 'r'?

• A. 0.5 Ω
• B. 1 Ω
• C. 2 Ω
• D. 4 Ω