# Test - Physics - 3

## 20 Questions MCQ Test Current Affairs & General Knowledge | Test - Physics - 3

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Attempt Test - Physics - 3 | 20 questions in 20 minutes | Mock test for CLAT preparation | Free important questions MCQ to study Current Affairs & General Knowledge for CLAT Exam | Download free PDF with solutions
QUESTION: 1

### Which of the following is used for regulated electric supply?

Solution:

The Zener diode is like a generalpurpose signal diode. When based in the forward direction it behaves just like a normal signal diode, but when a reverse voltage is applied to it, the voltage remains constant for a wide range of currents and hence widely used for regulated electric supply. The device was named after Clarence Zener, who discovered this electrical property. Many diodes described as "Zener" diodes rely instead on avalanche breakdown as the mechanism.

QUESTION: 2

### What is found in frequency modulation?

Solution:

Frequency modulation (FM) conveys information over a carrier wave by varying its instantaneous frequency. This contrasts with amplitude modulation, in which the amplitude of the carrier is varied while its frequency remains constant. Frequency modulation is also used in telemetry, radar, seismic prospecting and newborn EEG seizure monitoring.

QUESTION: 3

### When the speed of car is doubled, then what will be the braking force of the car to stop it in the same distance?

Solution:

Brake force, also known as Brake Power, is a measure of braking power of a vehicle. Suppose a car whose mass is 'x' and is braked from a speed of y km/hr to come to halt at a uniform retardation in z min. If the speed of the car is doubled in the same distance, then the braking force required to stop the car is four times the original speed i.e. '4v'. Note that all the parameters remain to be same.

QUESTION: 4

What is the maximum value of deforming force up to which a material shows elastic property and above which the material loses it?

Solution:

The Maximum Extent to which a solid may be stretched without permanent alteration of size or shape.

QUESTION: 5

The method of protecting iron from rusting, by coating a thin layer of Zinc is called -

Solution:

Galvanisation or galvanization (or galvanizing as it is most commonly called) is the process of applying a protective zinc coating to iron or steel, to prevent rusting.

QUESTION: 6

Ultra violet radiations of the Sun do not reach the earth because, earth's atmosphere is surrounded by –

Solution:

The ozone layer absorbs 97-99% of the Sun's medium-frequency ultraviolet light (from about 200 nm to 315 nm wavelength), which potentially damages exposed life forms on Earth. Ozone is formed from dioxygen by the action of ultraviolet light and also atmospheric electrical discharges, and is present in low concentrations throughout the Earth's atmosphere. In total, ozone makes up only 0.6 parts per million of the atmosphere.

QUESTION: 7

"Curie" is unit of :

Solution:

Curie, in physics, unit of activity of a quantity of a radioactive substance, named in honour of the French physicist Marie Curie. One curie (1 Ci) is equal to 3.7 x 1010 Becquerel (Bq). Radioactivity refers to the particles which are emitted from nuclei as a result of nuclear instability.

QUESTION: 8

Q.48) Speed of sound is the greatest in :

Solution:

Sound travels faster in liquids and non-porous solids than it does in air. It travels about 4.3 times as fast in water (1,484 m/s), and nearly 15 times as fast in iron (5,120 m/s), than in air at 20 degrees Celsius.

QUESTION: 9

Laser is a device to produce -

Solution:

In physics, two wave sources are perfectly coherent if they have a constant phase difference and the same frequency, and the same waveform. Coherence is an ideal property of waves that enables stationary (i.e. temporally and spatially constant) interference.

QUESTION: 10

The hydraulic brakes used in automobiles is a direct application of :

Solution:

Pascal's principle guarantees that the pressure is transmitted equally to all parts of the enclosed fluid system. This gives straightline braking unless there is a fluid leak or something to cause a significant difference in the friction of the surfaces. The hydraulic brake is an arrangement of braking mechanism which uses brake fluid, typically containing ethylene glycol, to transfer pressure from the controlling unit, which is usually near the operator of the vehicle, to the actual brake mechanism, which is usually at or near the wheel of the vehicle.

QUESTION: 11

A kilowatt-hour is unit of –

Solution:

Work is defined as a force acting through a distance (a length of space), energy is always equivalent to the ability to exert pulls or pushes against the basic forces of nature, along a path of a certain length. In the International System of Units (SI), energy is measured in joules, but in many fields other units, such as kilowatt-hours and kilocalories, are customary.

QUESTION: 12

Which of the following is used to split white light into different colours?

Solution:

In optics, a prism is a transparent optical element with flat, polished surfaces that refract light. At least two of the flat surfaces must have an angle between them. The exact angles between the surfaces depend on the application. The traditional geometrical shape is that of a triangular prism with a triangular base and rectangular sides, and in colloquial use "prism" usually refers to this type.

QUESTION: 13

Nuclear reactors used to produce electricity are based on –

Solution:

A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid (water or gas), which runs through turbines that power either ship's propellers or generators.

QUESTION: 14

Energy that is produced commercially from coal is called –

Solution:

Thermal enemy, but in most cases coal is used for electricity. The steel industry uses coal (or coke rather) in blast furnaces. Thermal energy is the part of the total internal energy of a thermodynamic system or sample of matter that results in the system temperature. This quantity may be difficult to determine or even meaningless unless the system has attained its temperature only through heating, and not been subjected to work input or output, or any other energy-changing processes.

QUESTION: 15

Which among the following is not a characteristic of transition metals?

Solution:

The transition metals have a tendency to lose electrons. Since the electrons in the highest energy level are actually on a lower principal energy number than the ones before them, this makes it relatively easy to lose some or all of their electrons to land in stable state.

QUESTION: 16

Which one of the following is not a function of the liver?

Solution:

Liver is the body’s largest internal organ. It has many functions in the body like it helps in protein synthesis and blood clotting, manufacturing triglycerides and cholesterol, glycogen synthesis, and bile production.

QUESTION: 17

The source of the Sun's energy is the process of –

Solution:

Nuclear fusion is a nuclear reaction in which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. During this process, matter is not conserved because some of the mass of the fusing nuclei is converted to energy which is released. Fusion is the process that powers active stars.

QUESTION: 18

A boy sitting in a train moving with a uniform velocity drops a coin outside. A man standing outside the train will find the trajectory of the coin to be -

Solution:

Parabola, because when the coin is dropped at a particular point, it has the same velocity as the running train. So, by Newton's first law, it continues its motion horizontally with that velocity.

QUESTION: 19

Which of the following is a nonrenewable source of energy?

Solution:

A non-renewable resource is a natural resource which cannot be reproduced, grown, generated, or used on a scale which can sustain its consumption rate. So, coal is nonrenewable source of energy. Once it is depleted, there is no more available for future needs. Fossil fuels (such as coal, petroleum, and natural gas), nuclear power (uranium) and certain aquifers are examples of non-renewable resources.

QUESTION: 20

Solar energy is converted into chemical energy during –

Solution:

In photosynthesis, solar energy is converted to chemical energy. The chemical energy is stored in the form of glucose (sugar). Carbon dioxide, water, and sunlight are used to produce glucose, oxygen, and water. Photosynthesis is a process used by plants and other organisms to convert the light energy captured from the sun into chemical energy that can be used to fuel the organism's activities.

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