JAMB Physics Past Questions & Answers - Page 160

796.

The external parts of an object can be measure accurately through the use of which scientific instrument?

A.

Micrometer screw gauge

B.

Vernier Caliper

C.

Meter rule

D.

None of the instrument

Correct answer is B

Vernier calliper is used to measure the internal and external diameter of an object

797.

What is the relationship mechanical advantage (MA) velocity Ratio (V.R) and efficiency with percentage?

A.

e = M.A/V.R × 100 %

B.

M.A = E.V.R

C.

V.R = 1 ÷ sin θ M.A

D.

M.A = 1/E × 100%

Correct answer is A

The relationship between M.A, V.R, e and 100% can be written as

e = M.A/V.R × 100 %

i.e E/100 = M.A/V.R

= L ÷ E/x ÷ y = Ly/Ex

E/100 = Ly/Ex

798.

Electrons were discovered by

A.

James Chadwick B.

B.

J.J Thompson

C.

Sir Isaac Newton

D.

Charles Newton

Correct answer is B

J.J. Thompson discovered ELECTRONS

799.

Mr. F. Abioye observed his image through a plane mirror, kept at a distance 4.7m away from him in his room. At what distance is the image found from Abioye's eye?

A.

9.4m

B.

7.5m

C.

5.7m

D.

6.9m

Correct answer is A

As object and image are usually at equal distance apart from the mirror /p>

Distance between Abioye (a) and hip image (I) = AI

i.e. AI = 4.7 + 47

= 9.4m

800.

Calculate the gravitation force of attraction between two planets of 1024kg and 1027kg separated by a distance of 1020meters.

A.

6.67N

B.

6.56N

C.

7.5N

D.

8.6N

Correct answer is A

F = (Gm1m2) ÷ r2

M1 = 1024Kg, M2 = 1027Kg , r = 102

(Note: the gravitational constant of G = \(6.67 × 10^{ 7ndash; 11}\) \( Nm^2/Kg^2 \)

F = \( (6.67 × 10^{– 11 + 24 + 27)} 10^40 = 6.67 × (10^40 ÷ 10^40)

= 6.67N

f = 6.67N