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When photons of energy 4.25 eV strike the surface of metal A, the ejected photoelectrons have maximum kinetic energy. TA eV and be broglie wavelength (A. The maximum kinetic energy of photoelectrons liberated from another metal B by photons of energy 4.70 eV is TB= (TA-1.50)eV. If the be Broglie wavelength of these photoelectrons is (B=2(A. then

The work function of A is 2.25 eV

The work function of B is 4.20 eV.

TA =2.00 eV.

TB= 2.75 eV

1, 2 and 3

2, 3 and 4

A transistor is used in the common emitter mode as an amplifier. Then

The base-emitter junction is forward-biased.

The base-emitter junction is reverse-biased

The input signal is connected in series with the voltage applied to bias the base-emitter junction.

The input signal is connected in series with the voltage applied to bias the base-collector junction

1 and 3

2 and 4

The electron in a hydrogen atom makes a transition n1( n2 where n1 and n2 are the principal quantum numbers of the two states. Assume the Bohr model to be valid. The time period of the electron in the initial state is eight times that in the final state. The possible values of n1 and n2 are

n1=4, n2=2

n1 =8, n2=2

n1=8, n2=1

n1=6, n2=3

1 and 4

2 and 3

In a p-n junction diode not connected to any circuit.

The potential is the same everywhere

The p-type side is at a higher potential than the n-type side.

There is an electric field at the junction directed from the n-type side to the p-type side.

There is an electric field at the junction directed from the p-type side to the n-type side.

The half-life of 131I is 8 days. Given a sample of 131I at time t=0, we can assert that

No nucleus will decays before t=4 days

No nucleus will decay before t=8 days.

All nuclei will decay before t= 16 days

A given nucleus may decay at any time after t=0

The work function of a substance is 4.0 eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately

540 nm

400 nm

310 nm

220 nm

The half-life period of a radioactive element X is same as the mean-life time of another radioactive element Y. initially both of them have the same number of atoms. Then

X and Y have the same decay rate initially.

X and Y decay at the same rate always

Y will decay at a faster rate than X

X will decay at a faster rate than Y

The potential difference applied to an X-ray tube is increased. As a result, in the emitted radiation

The intensity increases

The minimum wavelength increase

The intensity remain unchanged

The minimum wavelength decreases

1 and 2

3 and 4

A fresh prepared radioactive source of half life 2hremits radiation of intensity witch is 64 times the permissible safe level. The minimum time after witch it would be possible to work safely with this source is

6 hr

12 hr

24 hr

128 hr

The decay constant of a radioactive sample is (. The half-life and mean-life of the sample are respectively given by:

I/( and (in 2)/(

(In 2) ( and I/(

( (In 2) and I/(

( /(In2) and I/(

The work function of A is 2.25 eV

The work function of B is 4.20 eV.

TA =2.00 eV.

TB= 2.75 eV

1, 2 and 3

2, 3 and 4

A transistor is used in the common emitter mode as an amplifier. Then

The base-emitter junction is forward-biased.

The base-emitter junction is reverse-biased

The input signal is connected in series with the voltage applied to bias the base-emitter junction.

The input signal is connected in series with the voltage applied to bias the base-collector junction

1 and 3

2 and 4

The electron in a hydrogen atom makes a transition n1( n2 where n1 and n2 are the principal quantum numbers of the two states. Assume the Bohr model to be valid. The time period of the electron in the initial state is eight times that in the final state. The possible values of n1 and n2 are

n1=4, n2=2

n1 =8, n2=2

n1=8, n2=1

n1=6, n2=3

1 and 4

2 and 3

In a p-n junction diode not connected to any circuit.

The potential is the same everywhere

The p-type side is at a higher potential than the n-type side.

There is an electric field at the junction directed from the n-type side to the p-type side.

There is an electric field at the junction directed from the p-type side to the n-type side.

The half-life of 131I is 8 days. Given a sample of 131I at time t=0, we can assert that

No nucleus will decays before t=4 days

No nucleus will decay before t=8 days.

All nuclei will decay before t= 16 days

A given nucleus may decay at any time after t=0

The work function of a substance is 4.0 eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately

540 nm

400 nm

310 nm

220 nm

The half-life period of a radioactive element X is same as the mean-life time of another radioactive element Y. initially both of them have the same number of atoms. Then

X and Y have the same decay rate initially.

X and Y decay at the same rate always

Y will decay at a faster rate than X

X will decay at a faster rate than Y

The potential difference applied to an X-ray tube is increased. As a result, in the emitted radiation

The intensity increases

The minimum wavelength increase

The intensity remain unchanged

The minimum wavelength decreases

1 and 2

3 and 4

A fresh prepared radioactive source of half life 2hremits radiation of intensity witch is 64 times the permissible safe level. The minimum time after witch it would be possible to work safely with this source is

6 hr

12 hr

24 hr

128 hr

The decay constant of a radioactive sample is (. The half-life and mean-life of the sample are respectively given by:

I/( and (in 2)/(

(In 2) ( and I/(

( (In 2) and I/(

( /(In2) and I/(

These tests are meant for students of class xii. Students preparing for entrance tests should find them helpful Topics : photoelectricity,transistors, p-n junctios,half life etc

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