PHYSICS : REVISION TEST ON TOPICS OF CLASS XII ---I

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/(
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Description:

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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Kajal Sengupta
Physics 9th to 12 th grade,CIE, Edexcel, AP, IB , CBSE, ICSE
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