Q. Resistivity of a given conductor depends upon

1. temperature
2. length of conductor
3. area of cross section
4. shape of the conductor

Q. The ratio of current density and electric field is called

1. Resistivity
2. Conductivity
3. Drift velocity
4. Mobility

Q. In ${\beta }^{-}$ decay, a

1. neutron converts into a proton emitting antineutrino.
2. neutron converts into a proton emitting neutrino.
3. proton converts into a neutron emitting antineutrino.
4. proton converts into a neutron emitting neutrino.

Q. The material which is not suitable for making a permanent magnet is

1. Steel
2. Ticonal
3. Lead
4. Alnico

Q. A welder wears special glasses to protect his eyes mostly from the harmful effect of

1. Very intense visible light
2. infrared radiation
3. ultraviolet rays
4. microwaves.

Q. In an n-type semiconductor, the donor energy level lies

1. at the centre of the energy gap
2. just below the conduction band.
3. just above the valance band.
4. in the conduction band.

Q. When two nuclei $(A\le 10)$ fuse together to form a heavier nucleus, the

1. binding energy per nucleon increases.
2. binding energy per nucleon decreases.
3. binding energy per nucleon does not change.
4. total binding energy decreases.

Q. Electromagnetic waves used as a diagnostic tool in medicine are

1. X-rays
2. ultraviolet rays
3. infrared radiation.
4. ultrasonic waves.

Q. At equilibrium, in a p-n junction diode the net current is

1. due to diffusion of majority charge carriers.
2. due to drift of minority charge carriers
3. zero as diffusion and drift currents are equal and opposite.
4. zero as no charge carriers cross the junction.

Q. An electron is released from rest in a region of uniform electric and magnetic field acting parallel to each other. The electron will

1. move in a straight line
2. move in a circle
3. remain stationary
4. move in a helical path.

Q. Fill in the blank with appropriate answer :
Electric flux through a spherical surface shown in the figure, is _______ .

Q. Fill in the blank with appropriate answer :
Out of red, blue and yellow lights, the scattering of _____ light is maximum.

Q. Fill in the blank with appropriate answer :
A compound microscope is used because a realistic simple microscope does not have _______ magnification.

Q. Fill in the blank with appropriate answer :
An unpolarised light of intensity $I_0$ is passed through a polaroid. The intensity of plane polarised light obtained is ______ .

Q. Fill in the blank with appropriate answer :
In Young's double slit experiment, the path difference between two interfering waves at a point on the screen is $\frac{5\lambda }{2},\lambda$ being wavelength of the light used. The ______ dark fringe will lie at this point.

Q. Fill in the blank with appropriate answer :
If one of the slits in Young's double slit experiment is fully closed, the new pattern has _______ central maximum in angular size.

Q. Answer the following :
Define the term 'threshold frequency' in photoelectric emission.

Q. Answer the following :
A metallic rod $PQ$ of length $l$ is rotated with an angular velocity $\omega$ about an axis passing through its mid-point (O) and perpendicular to the plane of the paper, in uniform magnetic field $\overrightarrow{B}$, as shown in the figure. What is thee potential difference developed between the two ends of the rod, P and Q ?

Q. Answer the following:
What is the impedance of a capacitor of capacitance C in an AC circuit using source of frequency n Hz?

Q. Answer the following :
What is the value of impedance of a resonant series LCR circuit?

Q. Answer the following:
The threshold wavelength for two photosensitive surfaces A and B are ${\lambda }_1$ and ${\lambda }_2$, respectively. What is the ratio of the work functions of the two surface?

Q. Answer the following:
Draw the graph showing variation of the value of the induced emf as a function of rate of change of current flowing through an ideal inductor.

Q. Which of thee following electromagnetic waves has (a) minimum wavelength, and (b) minimum frequency? Write one use of each of these two waves.
Infrared waves, Microwaves, y-rays and X-rays

Q. A galvanometer of resistance $16\Omega$ shows full scale deflection for a current of $4mA$. How will you convert it into a voltmeter to measure a voltage up to $3V$?

Q. Draw V-I characteristics of a p-n junction diode. Explain, why the current under reverse bias is almost independent of the applied voltage up to the critical voltage.

Q. Define the term 'mobility' of' charge carriers in a current carrying conductor. Obtain the relation for mobility in terms of relaxation time.

Q. Define the term 'drift velocity' of electrons in a current carrying conductor. Obtain the relationship between the current density and the drift velocity of electrons.

Q. The focal length of an equiconcave lens is $\frac{3}{4}$ times of radius of curvature of its surfaces. Find the refractive index of the material of the lens. Under what condition will this lens behave as a converging lens ?

Q. For a radioactive substance, show the variation of the total mass disintegrated as a function of time t graphically.

Q. Initial mass of a radioactive substance is 3.2 mg. It has a half-life of 4 h. Find the mass of the substance left undecayed after 8 h.