Test: Physics - 1


20 Questions MCQ Test Science & Technology for UPSC CSE | Test: Physics - 1


Description
Attempt Test: Physics - 1 | 20 questions in 20 minutes | Mock test for UPSC preparation | Free important questions MCQ to study Science & Technology for UPSC CSE for UPSC Exam | Download free PDF with solutions
QUESTION: 1

An iron needle sinks in water whereas a ship made of iron floats on it because

Solution:

Because the specific gravity of the needle is greater than that of water displaced by it. Specific gravity (or relative density) = Density of the substance / Density of the water at 4°C The average density of iron needle is greater than water, therefore, it sinks.

QUESTION: 2

The cloudy nights are warmer than clear nights because

Solution:

The cloudy nights are warmer because clouds prevent escape of radiation of heat from the ground and the air.

QUESTION: 3

Food gets cooked faster in a pressure cooker because

Solution:

At that pressure, water boils at 121°C (250°F). That means food can cook at a much higher temperature than it ever could at atmospheric pressure—and since cooking reactions speed up at higher temperatures, your food cooks faster.

QUESTION: 4

It is more comfortable to wear white cloths in summer because

Solution:

The white clothes reflect heat falling on them in summer and they absorb the least from the sun.

QUESTION: 5

Of the two bulbs in a house, one glows brighter than the other. Which of the following statements is correct?

Solution:

The dimmer bulb has larger resistance than the brighter one. Power of the bulb ∝ 1 / Resistance Resistance is the obstruction offer to the flow of current.

QUESTION: 6

A fluorescent tube is preferred to an electric bulb because

Solution:

In a fluorescent tube, electrical energy is almost converted into light. The inner wall of the fluorescent tube is coated with phosphorus which immediately transformed into bright light.

QUESTION: 7

Consider the following statements in respect of a jet engine and a rocket:
1. A jet engine uses the surrounding air for its oxygen supply and so is unsuitable for motion in space.
2. A rocket carries its own supply of oxygen in the gas form as a fuel.

Q. Which of the above statement(s) is/are correct?

Solution:

In respect of a jet engine and a rocket, both the given statements are correct.

QUESTION: 8

The leaning tower of Pisa does not fall because

Solution:

Because the vertical line through the centre of gravity of the tower falls within the base.

QUESTION: 9

 Electronic motors operating at low voltages tend to burn out because

Solution:

Electronic motors draw more current which is inversely proportional to the voltage, therefore, more heat H = I2Rt is generated.

QUESTION: 10

If the doors of a refrigerator are left open for a few hours, the room temperature will

Solution:

If the doors of a refrigerator are left open for a few hours, the room temperature will increases. It is because system releases heat to the surroundings.

QUESTION: 11

If a rock is brought from the surface of the moon to the earth, then

Solution:

If a rock is brought from the surface of the moon to the earth, its weight will change but not its mass. Mass is a invariant physical quantity whereas weight of a body (w = mg) is variable as the value of acceleration due to gravity (g) changes.

QUESTION: 12

Match List-I with List-II and select the correct answer using the codes given below the lists:

Solution:

Wavelength is the distance between two consecutive crests or troughs and 1 angstrom = 10–10m, joule is the unit of energy. Intensity of sound is measured in decibel. Frequency is measured in hertz (Hz).

QUESTION: 13

Match List-I with List-II and select the correct answer with the help of codes given below:

 

Solution:

The unit of temperature is kelvin, power is measured in watt, pressure in pascal and force in newton.

QUESTION: 14

Which one of the following statements is not true about cosmic rays?

Solution:

Cosmic rays have very high frequency >1023 Hz and wavelength <10–24 m.

QUESTION: 15

Pendulum clocks become slow in summer because

Solution:

Pendulum clocks become slow in summer because the length of the pendulum increases. Increase in length ∆l = lo α ∆T where lo = original length, α = coefficient of linear expansion and ∆T = change in temperature.

QUESTION: 16

Consider the following statements and select the correct code:
Assertion (A): A piece of ice added to the drink cools it.
Reason (R): Ice takes latent heat from the drink for melting resulting in the cooling of the drink.

Solution:

A piece of ice added to the drink cool it because ice takes latent heat from the drink for melting resulting in the cooling of the drink.

QUESTION: 17

Match List-I with List-II and select the correct answer using the codes given below the lists:

Solution:

Revolver was discovered by Colt. Dynamite was discovered by Alfred Nobel. Law of cooling was discovered by Newton and law of pressure by Pascal.

QUESTION: 18

The atmosphere exerts enormous pressure on us. But, we don’t feel it because

Solution:

We don’t feel the atmospheric pressure because our blood exerts a pressure slightly more than that of the atmosphere.

QUESTION: 19

Which one of the following statements is not true for a person suffering from hypermetropia?

Solution:

Hypermetropia is corrected by using a convex lens.

Myopia is corrected by concave lens.

QUESTION: 20

Consider the following statements and select the correct answer using the codes given below:
Assertion (A): If ice collects on the freezer, the cooling in the refrigerator is affected adversely.
Reason (R): Ice is a poor conductor.

Solution:

If ice collects on the freezer, the cooling in the refrigerator is affected adversely because ice is a poor conductor of heat.

Use Code STAYHOME200 and get INR 200 additional OFF
Use Coupon Code

How to Prepare for UPSC

Read our guide to prepare for UPSC which is created by Toppers & the best Teachers

Download free EduRev App

Track your progress, build streaks, highlight & save important lessons and more!

Related tests