NECO Physics Past Questions & Answers - Page 23

111.

An object is placed in front of a concave mirror whose radius of curvature is 12cm. If the magnification of the Image produced is 1.5, how far is the object from the mirror?

A.

8cm

B.

10cm

C.

15cm

D.

18cm

E.

20cm

Correct answer is B

Radius of curvature(r)=12cm

focal length(F) = r ÷ 2 → 12 ÷ 2 = 6cm

therefore F = 6cm

magnification(M) = v ÷ u

1.5 = v ÷ u

:v = 1.5u

Using mirror formula

1/f =1/v + 1/u

\(\frac{1}{6}\) =\(\frac{1}{1.5u}\) + \(\frac{1}{u}\)

\(\frac{1}{6}\) = \(\frac{1 + 1.5}{1.5u}\)

\(\frac{1}{6}\) = \(\frac{2.5}{1.5u}\)

1 * 1.5u = 2.5 * 6

u = \(\frac{15}{1.5}\) = 10

therefore object distance =10cm.

112.

The angle between the geographic and the magnetic meridians at a place on the earth’s surface is the

A.

angle of declination

B.

angle of depression

C.

angle of dip

D.

latitude of the place

E.

longitude of the place

Correct answer is A

No explanation has been provided for this answer.

113.

A resistor connected in parallel with a galvanometer so that a large amount of current can be measured is called a/an

A.

ammeter

B.

avometer

C.

coil resistor

D.

multiplier

E.

shunt

Correct answer is E

No explanation has been provided for this answer.

114.

The relative density of dilute tetraoxosulphate (vi) acid in a battery is measured with a

A.

barometer

B.

hydrometer

C.

manometer

D.

hypsometer

Correct answer is B

No explanation has been provided for this answer.

115.

Calculate the energy stored in an inductor of inductance 0.5H when a current of 3A flows through it.

A.

15.00 J

B.

9.45 J

C.

6.00 J

D.

4.50J

E.

2.25 J

Correct answer is E

No explanation has been provided for this answer.