Processing math: 100%

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.

HOT! Click here to get our updates directly on your WhatsApp

186.

The periodic rise and fall in the intensity of sound produced whn two notes of nearly equal frequencies are sounded together is called?

doppler effect

beat

interference

resonance

View answer & explanation

Correct answer is B

beat, in physics, the pulsation caused by the combination of two waves of slightly different frequencies

187.

An object is placed at different distances, u, from a converging lens of focal length, 15.0cm. For what value of u does the lens act as a microscope?

u = 15cm only

u = 30cm only

M < 15cm only

u > 30cm only

View answer & explanation

Correct answer is D

Objects at a distance greater than two times of the focal length produces a real image, inverted and diminished in size.

→ 2 * 15 = 30cm

: At >30cm this is applicable

188.

A freely suspended compass needle on the earth's surface settles in a plane called----------

geographic meridian

magnetic meridian

magnetic declination

isoganals

View answer & explanation

Correct answer is B

The magnetic meridian is an equivalent imaginary line connecting the magnetic south and north poles and can be taken as the horizontal component of magnetic force lines along the surface of the earth. Therefore, a compass needle will be parallel to the magnetic meridian

189.

The efficiency of a wheel and axle is 100% and the ratio of their radii is 5:1. calculate the effort required to lift a load of mass 20kg using this machine, [g = 10 m s $^{-2}$ ]

20N

25N

40N

100N

View answer & explanation

Correct answer is C

VR = 5:1 or 5

Load = 20kg or 200N

MA = $\frac{200}{E}$

Efficiency% = $\frac{MA}{VR} * 100$

100% = $\frac{200}{5E} * 100$

5E = 200

E = 40

190.

Which of the following descriptions of the image formed by a plane mirror is not correct. the image is----

erect and of the same size as the object

laterally inverted and of the same size as the object

erect and bigger than the object

virtual and if the same size

View answer & explanation

Correct answer is C

Images formed by plane mirrors are virtual, upright, left-right reversed, the same distance from the mirror as the object's distance, and the same size as the object