Waec Physics 1993 Past Questions and Answers

Question 51:

• WAEC 1993

What amount of current would pass through a 10 Ω coil if it takes 21s for the coil to just melt a lump of ice of mass 10g at 0oC if there are no heat losses? (Latent heat of fusion of ice = 336 Jg\(^{-1}\)).

A. 16.00A
B. 4.00 A
C. 0.50A
D. 0.25A
E. 0.06 A

Question 52:

• WAEC 1993

How long does it take a 750 W heater operating at full rating to raise the temperature of 1 kg of water from 40^oC to 70^oC? (Take the specific heat capacity of water as 4200 J kg^-1 K^-1 and neglect heat losses).

A. 84s
B. 112s
C. 168s
D. 280s
E. 616s

Question 53:

• WAEC 1993

24 Na → 24 mg⁴ + X + energy 11 &nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp2 &nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp



The equation above represents a nuclear decay of sodium isotope. What is X?

A. Alpha particle
B. Beta particle
C. Gamma ray
D. X-ray
E. Neutron

Question 54:

• WAEC 1993

lf Einstein’s photoelectric equation is represented by hf - W = Φ where h is Planck’s constant, f the frequency of incident radiation and W the work function of the material, what does the symbol Φ up stand for?

A. Energy of the photons
B. Maximum Kinetic energy of the ejected electrons
C. Threshold frequency of the photons
D. Stopping potential of the electrons
E. Velocity of the electrons

Question 55:

• WAEC 1993

The phenomenon of radioactivity was first discovered by

A. Marie Curve
B. Sir J.J Thomson
C. Henn Becquerel
D. Niels Bohr
E. Enrico Fermi