Subject

Physics

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

51.

Mass of the proton is 1840 times that of electron. It is accelerated through a potential difference of 1V. Find its kinetic energy.

  • 6 eV

  • 2 eV

  • 10 eV

  • 1 eV


52.

The work function of a metal is 3.4 eV. If the frequency of incident radiation is increased to twice, then the work function of the metal becomes

  • 3.4 eV

  • 7.2 eV

  • 6.8 eV

  • 1.7 eV


53.

If red light is replaced by white light then width of diffraction pattern will

  • increases

  • decreases

  • a central white band is obtained

  • no effect


54.

In Planck's oscillator energy is given as

     E = exp Kt - 1   If K = 0, then energy would be

  • 0

  • Kt


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55.

A certain radioactive element has a half-life of 20 years. If we have a block with 10 g of the element in it, after how many years will there be just 2.5 g of the element in the block?

  • 80 years

  • 40 years

  • 100 years

  • 60 years


56.

Assertion:  Skiers uses air glasses. 

Reason:  Light reflected by snow is partially polarised.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If assertion is false but reason is true.


57.

Assertion:  LASER is used to measure distant object as moon. 

Reason: They are highly coherent source of light.

  • If both assertion and reason are true but reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not correct explanation of assertion.

  • If assertion is true but reason is false.

  • If assertion is false but reason is true.


58.

Assertion: During reverse biasing a diode doesn't conduct current. 

Reason: It narrows the depletion layer.

  • If assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion andreason are true and reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If assertion is false but reason is true.


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59.

Assertion: On increasing the frequency of light larger number of photoelectrons are emitted. 

Reason:  The number of electrons emitted depends on the intensity of incident light.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reasonn are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If assertion is false but reason is true.


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60.

Assertion:  Electric appliances with metallic body e.g., heaters, presses etc., have three pin connections, whereas an electric bulb has a two pin connection. 

Reason:  Three pin connections reduce heating of connecting cables.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are  true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If assertion is false but reason is true.


C.

If assertion is true but reason is false.

A 3-pin connection with a ground ( earth) wire is standard for anything that has a metal case or chassis that the user might touch during operation. The case is grounded so that there's a fault inside the appliances ( maybe a mouse ate the wiring) and live wire touches the cas, the breaker will trip rather than the case becoming energized at full mains voltage and potentially electrocutting someome who touched it.

The third pin is used for grounding purposes so that it leaves the user safe while handling the appliance by making the extra charge on it get discharged.


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