Waec Physics Past Questions For Year 1996
Question 46
Lenz's law of electromagnetic induction states that
- A. e.m.f. is induced in a circuit whenever there is a change in the magnetic flux linked with the circuit.
- B. the induced current in a conductor is in such a direction as to oppose the change producing it
- C. the magnitude of the induced e.m.f. in a circuit is proportional to the rate of change of the number of lines of force linking the circuit
- D. a force is exerted on a current-carrying conductor in a magnetic Held
- E. the induced charge is constant for a fixed change of flux.
Question 47
A wire of length 100cm and cross-sectional area of 2.0 x 10-3cm2 has a resistance of 0.10 Ω. Calculate its electrical conductivity.
- A. 5.0 x 107Ω-1cm-1
- B. 5.0 x 106Ω-1cm-1
- C. 2.0 x 106Ω-1cm-1
- D. 5.0 x 105Ω-1cm-1
- E. 2.0 x 106Ω-1cm-1
Question 48
The diagram above illustrates the conversion of a galvanometer of resistance 29 to an ammeter. The galvanometer gives a full-scale deflection for a current of 10mA. Calculate the value of R.
- A. 2.0 x 103 Ω
- B. 2.0 x 102 Ω
- C. 2.0 x 10-1 Ω
- D. 2.0 x 10-2 Ω
- E. 2.0 x 10-3 Ω
Question 49
The resistance in a series R-C circuit is 5 Ω. If the impedance of the circuit is 13 Ω, calculate the reactance of the capacitor
- A. 65 Ω
- B. 18 Ω
- C. 16 Ω
- D. 14 Ω
- E. 12 Ω
Question 50
ln the diagram above, the resistor has a resistance 8 Ω while the reactances of the inductor and the capacitor are 10 Ω and 16 Ω respectively Calculate the current in the circuit
- A. 3.6A
- B. 3.8A
- C. 9.2A
- D. 10.0A
- E. 13.0A
