Waec Physics 2020 Past Questions and Answers

Question 16:

• WAEC 2020

A 60kg man stands on a weighing balance in an elevator. If the elevator accelerates upwards at 5ms\(^{-2}\), determine the reading of the scale. [g = 10ms\(^{-2}\)]

A. 300N
B. 600N
C. 800N
D. 900N

Question 17:

• WAEC 2020

The length of an iron bar is 100cm at 20°C. At what temperature will its length increase by 0.01%? [Linear expansivity of iron = 1.2 x 10\(^{-5}\)°C]

A. 48.0°C
B. 38.0°C
C. 28.3°C
D. 23.0°C

Question 18:

• WAEC 2020

A moving-coil galvanometer which gives a full-scale on deflection with 0.005A is converted to a voltmeter reading up to 5V using an external resistance of 975\(\Omega\). What is the resistance of the metre?

A. 0.25\(\Omega\)
B. 2.50\(\Omega\)
C. 25.00\(\Omega\)
D. 250.00\(\Omega\)

Question 19:

• WAEC 2020

A beam consisting of \(\alpha\)-particles. \(\beta\)-particles and \(\gamma\)-rays pass through a magnetic field at right angles to the direction of the field. Which of the following observations would be made about the \(\alpha\)-particles, \(\beta\)-particles, and \(\gamma\)-rays respectively?

A. Deflected, deflected, deflected
B. Deflected, deflected, not deflected
C. Deflected, not deflected, deflected
D. Not deflected, deflected, deflected

Question 20:

• WAEC 2020

A parallel plate capacitor is charged and the charging battery is subsequently disconnected. lf the plates of the capacitor are moved farther apart by means of insulating handles, the

A. Capacitance would increase
B. Capacitance would decrease
C. Charge on the capacitor would increase
D. Charge on the capacitor would decrease