NECO Physics Past Questions & Answers - Page 22

106.

491 K is equivalent to

A.

273 °C

B.

218 °C

C.

373 °C

D.

491 °C

E.

764 °C

Correct answer is B

No explanation has been provided for this answer.

109.

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.

110.

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.