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Physics MCQs | Objective Type Questions SET-6
1.Which among the following is measured using a Vernier Caliper?
Answer: A [Dimensions]
Notes:
The Vernier caliper has a main scale and a sliding vernier scale which can measure nearest to 0.02 mm. It can be used to measure internal and the external dimensions of an object by using the smaller jaws at the top and the main jaws respectively. By using stems depth can be measured.
The Vernier caliper has a main scale and a sliding vernier scale which can measure nearest to 0.02 mm. It can be used to measure internal and the external dimensions of an object by using the smaller jaws at the top and the main jaws respectively. By using stems depth can be measured.
2.With reference to the virtual images and real images, consider the following statements:
1. While real image can be obtained on screen, virtual image cannot be obtained on screen.
2. While real image is always inverted, virtual image is always erect
Which among the above is / are correct statements?
1. While real image can be obtained on screen, virtual image cannot be obtained on screen.
2. While real image is always inverted, virtual image is always erect
Which among the above is / are correct statements?
Answer: C [ Both 1 & 2]
Notes:
Both are correct statements
Both are correct statements
3.The FM transmission of music is of very good quality in comparison to AM transmission. Consider the following statements with this reference:
- The AM signals are more susceptible to noise
- The FM receiver locks itself to catch stronger signal only
- The wavelength of AM waves is much higher in comparison to the FM waves
Which among the above is / are correct statements?
Answer: D [ 1, 2 & 3]
Notes:
The first statement is correct. Signal quality is a lot superior in FM than AM because the amplitude based signals are more susceptible to noise than those which use frequency. Further, the noise signals are difficult to filter out in AM reception whereas FM receivers easily filter out noise using the capture effect and pre-emphasis, de-emphasis effects. In capture effect, the receiver locks itself to catch stronger signal so that signals received are more synced with that at the transmitting end.
In pre-emphasis, de-emphasis process, the signal is further amplified to a higher frequency at sending end (pre-emphasis) and vice versa at receiver end (de-emphasis). These two processes reduce down the chances of a signal to get mixed with other signals and make FM more immune to noise than AM.
The third statement is also correct. AM waves work in the range of KHz while in FM waves work in MHz range. As a result, AM waves have a higher wavelength than the FM ones. A higher wavelength increases the range of AM signals as compared to FM which have a limited area of coverage.
The first statement is correct. Signal quality is a lot superior in FM than AM because the amplitude based signals are more susceptible to noise than those which use frequency. Further, the noise signals are difficult to filter out in AM reception whereas FM receivers easily filter out noise using the capture effect and pre-emphasis, de-emphasis effects. In capture effect, the receiver locks itself to catch stronger signal so that signals received are more synced with that at the transmitting end.
In pre-emphasis, de-emphasis process, the signal is further amplified to a higher frequency at sending end (pre-emphasis) and vice versa at receiver end (de-emphasis). These two processes reduce down the chances of a signal to get mixed with other signals and make FM more immune to noise than AM.
The third statement is also correct. AM waves work in the range of KHz while in FM waves work in MHz range. As a result, AM waves have a higher wavelength than the FM ones. A higher wavelength increases the range of AM signals as compared to FM which have a limited area of coverage.
4.Which of the following lie in the Tetra hertz frequency?
Answer: B [ Infra Red and Microwaves]
Notes:
The range of the tera hertz radiation frequency is from roughly 0.1 THz to 10 THz. It is higher than the frequency of radio waves and microwaves, but lower than the frequency of infrared light.
The range of the tera hertz radiation frequency is from roughly 0.1 THz to 10 THz. It is higher than the frequency of radio waves and microwaves, but lower than the frequency of infrared light.
5.Which among the following affect the propagation of the Radio Waves in the atmosphere of earth?
1. Reflection
2. Refraction
3. Diffraction
4. Absorption
Choose the correct option from the codes given below:
1. Reflection
2. Refraction
3. Diffraction
4. Absorption
Choose the correct option from the codes given below:
Answer: D [ 1, 2, 3 & 4]
Notes:
Like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization and scattering.
Like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization and scattering.
6.Consider the following statements with respect to the Thermionic emission:
1. It is caused by electrons or ions that break loose from the metal surface due to heat energy
2. A metal cannot emit thermions at all temperatures
Which among the above statements is / are correct ?
1. It is caused by electrons or ions that break loose from the metal surface due to heat energy
2. A metal cannot emit thermions at all temperatures
Which among the above statements is / are correct ?
Answer: C [ Both 1 & 2]
Notes:
The thermionic emission is cased by electrons or ions that break loose from the metal surface due to heat energy. The minimum heat energy required to make a metal emit an electron (thermion), from its surface is called threshold energy or work function. Electron volt (eV): It is the smallest unit of work and is generally used to measure threshold energy. It is defined as the amount of work done, when a charge of 1.6 × 10–19 coulombs (charge of one electron), moves through two points in an electric field, at a potential difference of one volt. 1 eV = 1.6 × 10–19 C × V = 1.6 × l0–19 J. The minimum temperature at which a particular material emits thermions from its surface on heating is called threshold temperature. A metal cannot emit thermions at all temperatures. The thermions are emitted by a metal only when its temperature is higher than the threshold temperature. (b) 1eV = 1.6 × l0–19 C × 1 V = 1.6 × l0–19 J
The thermionic emission is cased by electrons or ions that break loose from the metal surface due to heat energy. The minimum heat energy required to make a metal emit an electron (thermion), from its surface is called threshold energy or work function. Electron volt (eV): It is the smallest unit of work and is generally used to measure threshold energy. It is defined as the amount of work done, when a charge of 1.6 × 10–19 coulombs (charge of one electron), moves through two points in an electric field, at a potential difference of one volt. 1 eV = 1.6 × 10–19 C × V = 1.6 × l0–19 J. The minimum temperature at which a particular material emits thermions from its surface on heating is called threshold temperature. A metal cannot emit thermions at all temperatures. The thermions are emitted by a metal only when its temperature is higher than the threshold temperature. (b) 1eV = 1.6 × l0–19 C × 1 V = 1.6 × l0–19 J
7.Why Air is poor conductor of heat energy?
- The air molecules are have large mean free paths
- There are no free electrons in air
Select the correct option from the codes given below:
Answer: A [ Only 1]
Notes:
The second statement proves that air is poor conductor of electricity and not heat. The first reason explains poor heat conductivity of air and both reasons explain poor electrical conductivity of air. Conduction is the means by which heat is transferred from one part of a body to another or between two touching objects. Heat flows from the warmer to the cooler (part of a) body in order to equalize temperature. Conduction actually occurs through molecular movement, with one molecule bumping into another. In air, molecules have a relatively large “mean free path”, which means they have to move a relatively long distance (on the order of tenths of microns for air at normal pressure). Solids are better conductor than liquids and liquids are better conductor than gases. Metals are very good conductors of heat, while air is very poor conductor of heat.
The second statement proves that air is poor conductor of electricity and not heat. The first reason explains poor heat conductivity of air and both reasons explain poor electrical conductivity of air. Conduction is the means by which heat is transferred from one part of a body to another or between two touching objects. Heat flows from the warmer to the cooler (part of a) body in order to equalize temperature. Conduction actually occurs through molecular movement, with one molecule bumping into another. In air, molecules have a relatively large “mean free path”, which means they have to move a relatively long distance (on the order of tenths of microns for air at normal pressure). Solids are better conductor than liquids and liquids are better conductor than gases. Metals are very good conductors of heat, while air is very poor conductor of heat.
8.Which of the following makes a CD or DVD show rainbow pattern?
Answer: A [ Diffraction of the Light]
Notes:
A CD or DVD has closely spaced tracks which work as a diffraction grating to form the familiar rainbow pattern seen when looking at a disk.
A CD or DVD has closely spaced tracks which work as a diffraction grating to form the familiar rainbow pattern seen when looking at a disk.
9.The force that binds the neutrons and protons in a nucleus is called as:
Answer: B [Strong Nuclear Force]
Notes:
Strong Nuclear Force is the force that binds the neutrons and protons together in a nucleus. Nuclear forces are the strongest forces in nature are 10^38 times stronger than gravitational forces. Nuclear forces have the shortest range and operate within the nucleus only.
Strong Nuclear Force is the force that binds the neutrons and protons together in a nucleus. Nuclear forces are the strongest forces in nature are 10^38 times stronger than gravitational forces. Nuclear forces have the shortest range and operate within the nucleus only.
10.By how many times are the Electrostatic forces stronger than the Gravitational Forces for a fixed distance?
Answer: B [1036]
Notes:
Electrostatic forces are 1036 times stronger than the Gravitational Forces for a fixed distance. Electrostatic forces may be attractive or repulsive depending upon the charges. Electrostatic forces are conservative forces and obey inverse square law.
Electrostatic forces are 1036 times stronger than the Gravitational Forces for a fixed distance. Electrostatic forces may be attractive or repulsive depending upon the charges. Electrostatic forces are conservative forces and obey inverse square law.
