51.

The current gain for a transistor working as common-base amplifier is 0.96. If the emitter current is 7.2 mA, then base current is

• 0.35 mA

• 0.28 mA

• 0.39 ma

• 0.43 mA

Photoelectric effect supports quantum nature of light because

• there is minimum frequency of light below which no photoelectrons are emitted

• the maximum energy of photoelectron depends only on the frequency of light and not on its intensity

• photoelectric effect is an instantaneous process

• all the above choices are correct

Assertion:  In optical fibre, the diameter of the core is kept small. 

Reason:  The smaller diameter of the core ensures that the fibres should have incident angle more than the critical angle required for total internal reflection.

• 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 both assertion and reason are false.

Assertion:  A p-n junction with reverse bias can be used as a photo-diode to measure light intensity. 

Reason:  In a reverse bias condition the current is small but it is more sensitive to change in intensity of incident light.

• 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 both assertion and reason are false.

Assertion:  The output voltage and the input voltage of the NOT gate have 180° phase difference. 

Reason:  The logic NOT can be built using diode.

• 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 both assertion and reason are false.

Assertion:  In a common emitter transistor amplifier, the input current is much less than the output current than output impedance. 

Reason:  The common emitter transistor amplifier has higher input impedance than output impedance.

• 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 both assertion and reason are false.

Assertion:  In a common emitter transistor amplifier, the input current is much less than the output current than output impedance. 

Reason: The common emitter transistor amplifier has higher input impedance than output impedance.

• 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 both assertion and reason are false.

Assertion:  If a heavy nucleus is split into two medium-sized parts, each of the nuclei will have more binding energy per nucleon than the original nucleus. 

Reason:  Joining two light nuclei together to give a single nucleus of medium size means more binding energy per nucleon than the two nucleus.

• 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 both assertion and reason are false.

Assertion: The frequencies of incident, reflected and refracted beam of monochromatic light passing from one medium to another are the same. 

Reason: The incident, the reflected and refracted rays are coplanar.

• 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 both assertion and reason are false.

Assertion:  A secondary rainbow have inverted colours than the primary rainbow. 

Reason:  The secondary rainbow is formed by single total internal reflection.

• 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 both assertion and reason are false.