Waec Physics 2018 Past Questions and Answers

Question 46:

• WAEC 2018

In a series R-L-C circuit, R = 10\(\Omega\), \(X_{c}\)= 4\(\Omega\) and \(X_{L}\) = 9\(\Omega\). The impedance of the circuit is

A. 4.1\(\Omega\)
B. 5.0\(\Omega\)
C. 10.8\(\Omega\)
D. 11.2\(\Omega\)

Question 47:

• WAEC 2018

A student uses two compass needles to investigate the magnetic field around a bar magnet. Which of the following diagrams show the correct directions of the needles?

A. A
B. B
C. C
D. D

Question 48:

• WAEC 2018

Which of the following is emitted in a process of natural radioactivity?

A. \(\alpha\)- particles and \(\beta\)- particles
B. \(\alpha\)- particles and X-rays
C. \(\beta\)- particles and X-rays
D. \(\lambda\)- rays and X-rays

Question 49:

• WAEC 2018

In which of the following situations is photoelectric effect employed?
I. Automatic devices for switching on light at dusk
II. Automatic doors in departmental stores
III. Automatic devices for switching on air conditioners
IV. Automatic voltage stabilizers

A. I, II and IV only
B. I, III and IV only
C. III and IV only
D. I and II only

Question 50:

• WAEC 2018

Which of the following radiations has the longest wavelength?

A. Gamma ray
B. Radio wave
C. Infrared ray
D. X-ray