Physics — Light, Sound, Electricity

Question 1

The mirror used in headlights is:‌​‍

Accepted Answer

Concave — Concave mirrors produce a focused beam of light — used in headlights, torches, and solar cookers.‌​‍

Answer

Plane

Answer

Convex

Answer

Cylindrical

Question 2

The lens used to correct myopia is:‌​‍

Accepted Answer

Concave — Myopia (short-sightedness) is corrected by concave (diverging) lens.‌​‍

Answer

Convex

Answer

Bifocal

Answer

Cylindrical

Question 3

White light splits into colours through a prism. This is called:‌​‍

Accepted Answer

Dispersion — Dispersion = splitting of white light into 7 colours (VIBGYOR) by a prism.‌​‍

Answer

Reflection

Answer

Refraction

Answer

Diffraction

Question 4

Sound cannot travel through:‌​‍

Accepted Answer

Vacuum — Sound needs a medium to travel. ‌​‍It cannot travel through vacuum (no molecules to vibrate).

Answer

Air

Answer

Water

Answer

Steel

Question 5

The unit of frequency is:‌​‍

Accepted Answer

Hertz — Hertz (Hz) = unit of frequency (cycles per second). ‌​‍Decibel = unit of sound intensity.

Answer

Decibel

Answer

Watt

Answer

Newton

Question 6

Ohm's Law states:‌​‍

Accepted Answer

V = IR — Ohm's Law: Voltage = Current × Resistance (V = IR).‌​‍

Answer

F = ma

Answer

E = mc²

Answer

PV = nRT

Question 7

Household wiring uses which circuit?‌​‍

Accepted Answer

Parallel — Parallel circuit — if one appliance fails, others keep working. ‌​‍Voltage remains same across all.

Answer

Series

Answer

Mixed

Answer

None

Question 8

The power consumed by an appliance is measured in:‌​‍

Accepted Answer

Watt — Power (P) = V × I, measured in Watts. 1 unit of electricity = 1 kWh.‌​‍

Answer

Volt

Answer

Ampere

Answer

Ohm

Question 9

Ultrasound has frequency above:‌​‍

Accepted Answer

20,000 Hz — Ultrasound = above 20,000 Hz (above human hearing range). ‌​‍Used in medical scans (sonography).

Answer

20 Hz

Answer

200 Hz

Answer

2,000 Hz

Question 10

A mirage is due to:‌​‍

Accepted Answer

Total internal reflection — Mirages are caused by total internal reflection of light in layers of hot air near the ground.‌​‍

Answer

Reflection

Answer

Dispersion

Answer

Diffraction

Question 11

The fuse wire in an electrical circuit is made of:‌​‍

Accepted Answer

Lead-tin alloy — Fuse wire is made of lead-tin alloy with low melting point — melts and breaks circuit during overload.‌​‍

Answer

Copper

Answer

Silver

Answer

Gold

Question 12

The colour of light with the longest wavelength is:‌​‍

Accepted Answer

Red — Red has the longest wavelength in visible spectrum. ‌​‍Violet has the shortest. (VIBGYOR order).

Answer

Violet

Answer

Blue

Answer

Green

Question 13

An echo is produced by:‌​‍

Accepted Answer

Reflection of sound — Echo = reflection of sound from a surface. ‌​‍Needs minimum 17.2m distance from the reflecting surface.

Answer

Refraction of sound

Answer

Absorption of sound

Answer

Diffraction of sound

Question 14

LED stands for:‌​‍

Accepted Answer

Light Emitting Diode — LED = Light Emitting Diode. Energy-efficient lighting technology.‌​‍

Answer

Light Emitting Device

Answer

Laser Emitting Diode

Answer

Low Energy Display

Question 15

The device used to measure electric current is:‌​‍

Accepted Answer

Ammeter — Ammeter measures current (connected in series). ‌​‍Voltmeter measures voltage (connected in parallel).

Answer

Voltmeter

Answer

Galvanometer

Answer

Ohmmeter

Physics — Light, Sound, Electricity