NECO Physics Past Questions & Answers - Page 10

46.

The work done in extending a spring by 40 mm is 1.52J. Calculate the elastic constant of the spring.

A.

38.8 Nm-1

B.

60.8 Nm-1

C.

190.0 Nm-1

D.

1900.0 Nm-1

E.

3800.0 Nm-1

Correct answer is D

Force = Elastic constant x extension

Work done = \(\frac{1}{2} K \times e^2\)

Given Work done = 1.52J; Elastic constant (k) = ?; e = 40mm = 0.04 m

\(\therefore 1.52 = \frac{k \times (0.04)^2}{2}\)

\(3.04 = k \times 1.6 \times 10^{-3}\)

\(k = \frac{3.04}{1.6} \times 10^3\)

= 1.9 x 10\(^3\)

= 1900 Nm\(^{-1}\)

47.

The electric potential at a distance d from a point charge q in air of permittivity eo is expressed as?

A.

q2 ÷ 4πeod

B.

q2 ÷ 4πeo

C.

q ÷ 4πeod2

D.

q ÷ 4πeod

E.

q ÷ 4πeo2d

Correct answer is D

The electric potential at a point in an electric field is defined as the amount of work done in moving a unit positive charge from infinity to that point against the action of the field.

V = \(\frac{Q}{4 π∈r}\) 

48.

Two images Y and X are formed by a plane mirror and a convex mirror respectively. Which of the following is correct about their characteristics?

A.

Both are inverted

B.

The magnification of Y is greater than one while that of X is one

C.

The magnification of Y is one while that of X is less than one

D.

Y is inverted while X is erect

E.

Y is real while X is virtual.

Correct answer is C

No explanation has been provided for this answer.

49.

In the electrical method of making a magnet, the polar the magnet formed depends on the

A.

amount of current passed

B.

direction of the current

C.

nature of the material used

D.

orientation of the magnetic material in space

E.

size of the magnetic material

Correct answer is B

No explanation has been provided for this answer.

50.

An object of mass 2kg moves for 5s with a uniform velocity of 10ms. What is the magnitude of its acceleration in ms-2

A.

zero

B.

2.5

C.

10

D.

12.5

E.

100

Correct answer is A

No explanation has been provided for this answer.