Physics questions and answers

Physics Questions and Answers

If you want to learn more about the nature and properties of matter and energy or you're simply preparing for a Physics exam, these Physics past questions and answers are ideal for you.

511.

When the downward current flows in a straight vertical conductor, the direction of its magnetic field at a point due north of the wire is?

A.

Upward

B.

North

C.

South

D.

West

Correct answer is D

At a point due N of the wire, the field is due west, at a point due S of the wire, the field is due eest.

512.

The pitch of a screw jack is 0.45cm and the arm is 60cm long. If the efficiency of the Jack is 75/π %, calculate the mechanical advantage.

A.

400

B.

300

C.

200

D.

150

Correct answer is C

P = 0.45cm, L = 60cm, Eff = 75/π%

VR (Screw system) = 2πr
P
= 2πL
P

 

M.A = Eff% × VR
100
= 75
π
× 1
100
× 2π × 60
0.45
= 75 × 800
300
= 200

 

514.

The pin-hole camera produces a less sharply defined image when the

A.

pin-hole is larger

B.

illumination is less

C.

screen is further from the pin-hole

D.

object is further from the pin-hole

Correct answer is A

- a less sharp or blurred image is due to increased brightness

- increase brightness is also due to large hole or many pin holes

515.

A ray of light passes through the centre of curvature of a concave mirror and strikes the mirror. At what angle is the ray reflected?

A.

180\(^o\)

B.

90\(^o\)

C.

0\(^o\)

D.

60\(^o\)

Correct answer is C

- a ray of light passing through the centre of a curvature is returned along the same path

- angle difference along the same path is zero