WAEC Physics Past Questions & Answers - Page 33

161.

The sketched graph above illustrates the heating curve of a 0.02kg of water. Determine the approximate value of the specific latent heat of vapourization of water
 

A.

2.25 x 10\(^6\) J kg\(^{-1}\)

B.

4.17 x 10\(^3\) J kg\(^{-1}\)

C.

2.00 x 10\(^3\) J kg\(^{-1}\)

D.

1.00 x 10\(^3\) J kg\(^{-1}\)

Correct answer is D

No explanation has been provided for this answer.

162.

Which of the following statements about photoelectrons is correct?

A.

A faint green light produces photoelectrons with less kinetic energy than a bright red light

B.

A red light releases a smaller number of electrons than a green light

C.

A faint green light produces photoelectrons with greater kinetic energy than a bright red light

D.

A red light produces more photoelectrons than a green light

Correct answer is B

No explanation has been provided for this answer.

163.

An electron of mass m and charge e moves in a circular path in a magnetic field of flux density B. How long does it take to complete one orbit? 

A.

\(\frac{2me}{B\pi}\)

B.

\(\frac{2B}{me\pi}\)

C.

\(\frac{2\pi m}{Be}\)

D.

\(\frac{Be}{2 \pi m}\)

Correct answer is C

Motion of charged particles in Magnetic field

qvb = \(\frac{Mv^2}{r}\)

where q = e

Introducing Period (T) as time taken to complete one orbit = \(\frac{2πM}{qe}\)

164.

Which of the following statements about the motion of a simple pendulum is true?

A.

It is a simple harmonic motion when the angle of displacement is large

B.

It passes the equilibrium position with minimum speed

C.

It possesses maximum kinetic energy at the extreme positions

D.

lt swings faster at the poles than at the equator

Correct answer is D

No explanation has been provided for this answer.

165.

The temperature of an object is raised by 120°C. The resulting increase in its absolute temperature is
 

A.

50K

B.

120 K

C.

200K

D.

393K

Correct answer is B

No explanation has been provided for this answer.