µ IB | Circuits + Cells

10 quick questions

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10 minutes maximum! (can you do it in 5?)

 

  • Potential Dividers
  • Internal resistance
  • Kirchoff's Laws
  • Cell properties

 1. Rechargeable cells have many applications. What is the name given to rechargeable cells, and which way must the current flow to recharge the cell?

Name Current flows...
A
Primary cell + to -
B
Primary cell - to +
C
Secondary cell + to -
D
Secondary cell - to +

2. Which of these statements best describes the discharge of a primary cell?

  • A. Loses its initial e.m.f. value quickly, then has a stable and constant lower value for most of its lifetime.
  • B. The initial e.m.f. decays gradually to zero over the lifespan of the cell.
  • C. The initial e.m.f. decays gradually to about 50% of the intial value, where it remains for some time.
  • D. Retains the initial e.m.f. for some time, before a rapid decay to zero.

 

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

potential divider

 

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

5-7. These questions are about Kirchoff's laws. The circuit below shows 2 cells of negligable internal resistance connected to 3 resistors:

Kirchoffs laws

 

5. Which of these statements about the currents I1, I2 and I3 is correct?

  • A. I1= I2 + I3
  • B. I1= I2 - I3
  • C. I2= I1 - I3
  • D. I2= I3 - I1

6. By applying Kirchoff's law to the upper loop in the circuit, the total e.m.f. can be equated to the sum of the voltage drops around the loop. Which of these statements is correct for the upper loop? (Top half of the circuit including the 6 V cell and the central resistor).

  • A. 6 = 4I1 + I2
  • B. 6 = 4I1 - I2
  • C. 2 = 4I1 + I2
  • D. 2 = 4I1 - I2

7. I2 is found to be 2 A. What is the value of I1?

  • A. 0 A
  • B. 1 A
  • C. 2 A
  • D. 4 A

 

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

internal resistance of a cell

 

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