Waec Physics 1998 Past Questions and Answers

Question 46:

• WAEC 1998

The direction of the magnetic field at a point in the vicinity of a bar magnetic is

A. Along the line joining the point to the neutral point
B. Always away from the south pole of the magnet
C. Opposite the direction of theresultant field at that point
D. Always towards the north pole of the magnet
E. The direction towards which the north pole of a compass needle would point

Question 47:

• WAEC 1998

The diagram below illustrates an a.c.source of 50V(r.m.s.), \(\frac{100}{\pi}\)Hz connected in series with an inductor of inductor of inductance L and a resistor of resistance R. The current in the circuit is 2A and the p.d across L and R are 30V and 40V respectively. Calculate the power factor of the circuit

A. 1.33
B. 1.25
C. 0.80
D. 0.75
E. 0.60

Question 48:

• WAEC 1998

The diagram below illustrates an a.c.source of 50V(r.m.s.), \(\frac{100}{\pi}\)Hz connected in series with an inductor of inductor of inductance L and a resistor of resistance R. The current in the circuit is 2A and the p.d across L and R are 30V and 40V respectively. Calculate the average power dissipated in the circuit

A. 100W
B. 80W
C. 60W
D. 20W
E. 10W

Question 49:

• WAEC 1998

Use the following data to determine the length L of a wire when a fore of 30N is applied, assuming Hooke's law is obeyed
\(\begin{array}{c|c}\text{Force applied/N} & 0 & 5 & 10 & 30\\ \hline \text{length of wire/mm} & 500.0 & 500.0 & 501.0 & L \end{array}\)

A. 3.0mm
B. 3.5mm
C. 503.00mm
D. 503.5mm
E. 506.0mm

Question 50:

• WAEC 1998

Which of the following explains the concave meniscus of water in a clean glass tube? the

A. Adhension between water and glass molecules is greater than the sdhension between water molecules
B. Cohension between water molecules is greater then the adhension between glass and water molecule
C. Molecules of water near the glass move faster than the molecules at the centre of the tube
D. Molecules of water at the water-air boundary are often attracted to the centre of the tube
E. Weight of the water pulls the centre part of the surface down