Waec Physics 1998 Past Questions and Answers

Question 41:

• WAEC 1998

A cell of e.m.f. 1.5v is connected in series with a resistor of 3\(\Omega\). A high resistance voltmeter connected across the cell registers only 0.9v. Calculate the internal resistance of the cell

A. 5.0\(\Omega\)
B. 4.5\(\Omega\)
C. 2.4\(\Omega\)
D. 2.0\(\Omega\)
E. 1.8\(\Omega\)

Question 42:

• WAEC 1998

Calculate the resistance of the filament of lamp rated at 240V 60W

A. 240\(\Omega\)
B. 360\(\Omega\)
C. 960\(\Omega\)
D. 144\(\Omega\)
E. 2880\(\Omega\)

Question 43:

• WAEC 1998

The diagram above illustrates a freely suspended bar magnet NS hanging from a point in a horizontal ceiling. The thread used for suspending the magnet and the axis of the magnet are as indicated on the diagram. The angle marked \(\theta\) is called the angle os

A. Depression
B. Declination
C. Variation
D. Elevation
E. Dip

Question 44:

• WAEC 1998

Lenz's law of electromagnet states that

A. The induced charge is constant for a fixed change of force
B. A force is exerted on a current-carrying conductor in a magnetic field
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. The induced current in a conductor is in such a direction as to oppose the change producing it
E. E.m.f. is induced in a circuit whenever there is a change in the magnetic flux linked with the circuit

Question 45:

• WAEC 1998

A proton of charge 1.6 x 10¹⁹C is projected into a uniform magnetic field of flux density with a constant speed of 1.6 x 10⁶ms^-1, calculate the magnitude of the force exerted on it by the field

A. 0.0N
B. 2.0 x 10^-21N
C. 1.3 x 10^-17N
D. 5.1 x 10^-14N
E. 2.3 x 10¹³N