Waec Physics 1996 Past Questions and Answers

Question 46:

• WAEC 1996

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 47:

• WAEC 1996

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:

• WAEC 1996

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 49:

• WAEC 1996

A cell of e.m.f. 1.5V is connected in series with a resistor of resistance 39. A high-resistance voltmeter connected across the cell registers only 0.9V. Calculate the internal resistance of the cell

A. 1.85Ω
B. 2.0Ω
C. 2.4Ω
D. 4.5Ω
E. 5.0Ω

Question 50:

• WAEC 1996

Soft iron is used in making the armature of an electric bell because it

A. Retains its magnetism for a longtime
B. Loses its magnetism readily
C. Produces permanent magnets
D. Is not easily magnetised
E. Decreases the magnetic effect of a direct current