JAMB Physics Past Questions & Answers - Page 396

1,976.

A charge 50 µc has electric field strength of 360 NC-1 at a certain point. The electric field strength due to another charge 120 µc kept at the same distance apart and in the same medium is?

A.

864 NC-1

B.

150 NC-1

C.

144 NC-1

D.

18 NC-1

Correct answer is A

In general, electric field strength E = (F)/q

E = \(\frac{q}{4\pi\varepsilon_0d^2}\)

⇒ 360 = \(\frac{9\times10^9\times50\times10^-6}{d^2}\)

solving, we have \(d^2\) = 1250

putting \(d^2\) = 1250 into the second equation,

E = \(\frac{9\times10^9\times120\times10^-6}{1250}\)

we have E = \(864NC^-1\) 

1,977.

The production of pure spectrum could easily be achieved using a?

A.

glass prism with a pin

B.

triangular prism with two convex lens

C.

traingular prism only

D.

triangular prism with two concave lenses

Correct answer is B

No explanation has been provided for this answer.

1,978.

When an object is placed between the principal focus and the optical center of a convex lens, it could be used as a?

A.

Simple microscope

B.

refecting lens

C.

compound microscope

D.

projector

Correct answer is A

No explanation has been provided for this answer.

1,979.

A glass plate 0.9cm thick has a reflective index of 1.50. how long does it take for a pulse of light to pass through the plate?

[c = 3.0 x 8 ms-1]

A.

4.5 x 10-11s

B.

4.5 x 10-10s

C.

4.5 x 10-12 s

D.

3.0 x 10-10s

Correct answer is A

N = 1.5 = (speed of light in glass)/speed of light in air
(1.5)/1 = (3.0 x 108)/V
V = (3.0 x 108)/1.5
V = 2.0 x 108 ms-1
But x = Vt
t = (x)/Vt
t = (x)/v = \( \frac{9 x 10^{-3}}{2.0 x 10^8}\) 
∴ Time = 4.5 x 10\(^{-11}\)S

1,980.

The instrument used by designers to obtain different color pattern is called?

A.

periscop

B.

sextant

C.

episcope

D.

kaleidoscope

Correct answer is D

No explanation has been provided for this answer.