Physics Question Answer For Competitive Exam Set-1

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Physics Question Answer For Competitive Exam Set-1

||Physics Question Answer For Competitive Exam Set-1||Physics Question Answer For Competitive Exam Set-1||

1. For which Diode is used ?

(A) modulation

(B) oscillation

(D) purification

Explanation:-The most common function of a diode is to allow an electric current to pass in one direction (called the diode’s forward direction), while blocking current in the opposite direction (the reverse direction).This unidirectional behavior is called rectification or verification and is used to convert alternating current to direct current, including extraction of modulation from radio signals in radio receivers— these diodes are forms of rectifiers diode is a twoterminal electronic component with an asymmetric transfer characteristic, with low (ideally zero) resistance to current flow in one direction, and high (ideally infinite) resistance in the other

2. Who among the following developed the technology of underground nuclear explosion ?

(A) Dr. Homi J. Bhabha

(B) Dr. Vikram Sarabhai

(D) Dr. P. K. Iyengar

Explanation:-Homi Jehangir Bhabha was an Indian nuclear physicist, founding director, and professor of physics at the Tata Institute of Fundamental Research. Colloquially known as “father of Indian nuclear programme,” Bhabha gained international prominence after deriving a correct expression for the probability of scattering positrons by electrons, a process now known as Bhabha scattering. His major contribution included his work on Compton scattering, R-process, and furthermore the advancement of nuclear physics. He was awarded Padma Bhushan by Government of India in 1954.

3. Which among the following types of coal produces most heat per unit ?

(A) Coal

(B) Lignite

(C) Anthracite

(D) Pit

Explanation:-The heat content of anthracite ranges from 22 to 28 million Btu per short ton (26 to 33 MJ/kg) on a moist, mineral-matter-free basis. Anthracite (“coallike”) is a hard, compact variety of mineral coal that has a high luster. It has the highest carbon content, the fewest impurities, and the highest calorific content of all types of coals, which also include bituminous coal and lignite. Anthracite is the most metamorphosed type of coal (but still represents low-grade metamorphism), in which the carbon content is between 92.1% and 98%

4. Which among the following waves is used for communication by artificial satellites ?

(A) Micro waves

(B) Radio waves

(D) Frequency of 1016 series

Explanation:-For fixed (point-to-point) services, communications satellites provide a microwave radio relay technology complementary to that of communication cables. They are also used for mobile applications such as communications to ships, vehicles, planes and handheld terminals, and for TV and radio broadcasting. Microwave technology is extensively used for pointto-point telecommunications (i.e., non broadcast uses). Microwaves are especially suitable for this use since they are more easily focused into narrow beams than radio waves, and also their comparatively higher frequencies allow broad bandwidth and high data flow.

5. What is found in frequency modulation ?

(A) Fixed frequency

(B) Fixed dimension

(D) Change in dimension only

Explanation:-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. Frequency modulation is known as phase modulation when the carrier phase modulation is the time integral of the FM signal. FM is widely used for broadcasting music and speech, two-way radio systems, magnetic taperecording systems and some video-transmission systems.

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

(A) four times

(B) two times

(D) one-fourth

Explanation:-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.

7. The dimension of which of the following is the same as that of impulse ?

(A) Volume

(B) Momentum

(D) Change in the rate of momentum

Explanation:-The quantity of impulse is force × time interval. In classical mechanics, linear momentum or translational momentum is the product of the mass and velocity of an object. For example, a heavy truck moving fast has a large momentum—it takes a large and prolonged force to get the truck up to this speed, and it takes a large and prolonged force to bring it to a stop afterwards. If the truck were lighter or moving slower, then it would have less momentum.

8. Which among the following is the fundamental quantity ?

(A) Volume

(B) Time

(D) Force

Explanation:-The fundamental qualities of Physics are the seven basic quantities that can be used to express all other physical quantities. These are as follows: Length: Metre, Heat: Kelvin, Time: second, Luminous Intensity: Candela, Mass: Kilogram, Electric Current: Ampere, and Amount of substance: Moles.

9. When a ring of metal is heated what happens to its hole ?

(A) expands

(B) contracts

(D) it expands or contracts according to its coefficient of expansion

Explanation:-The hole size will increase because in expansion the size between two molecules do not increase so when the molecules on the outer edge move outward. Due to expansion, the size of the hole will also increase so as to compensate the distance change between the molecules. Thermal expansion is the tendency of matter to change in volume in response to a change in temperature. When a substance is heated, its particles begin moving more and thus usually maintain a greater average separation.

10. If the diameter of a capillary is doubled, then the rise of water in it will be

(A) two times

(B) half

(D) no change

Explanation:-Radius of a capillary tube is inversely proportional to the height of the liquid column. So, if radius of the tube is doubled, rise of level of water will becomes half of the previous rise in capillary tube. Capillary action, or capillarity, is the ability of a liquid to flow in narrow spaces without the assistance of, and in opposition to external forces like gravity. The effect can be seen in the drawing up of liquids between the hairs of a paint-brush, in a thin tube, in porous materials such as paper, in some non-porous materials such as liquefied carbon fiber, or in a cell. It occurs because of inter-molecular attractive forces between the liquid and solid surrounding surfaces