PUC Science 2nd PUC Class 12 - Karnataka Board PUC Question Bank Solutions for Physics

In the decay ⁶⁴Cu → ⁶⁴Ni + e⁺ + v, the maximum kinetic energy carried by the positron is found to be 0.650 MeV.
(a) What is the energy of the neutrino which was emitted together with a positron of kinetic energy 0.150 MeV?
(b) What is the momentum of this neutrino in kg m s⁻¹?
Use the formula applicable to a photon.

Carbon (Z = 6) with mass number 11 decays to boron (Z = 5). (a) Is it a β⁺-decay or a β⁻decay? (b) The half-life of the decay scheme is 20.3 minutes. How much time will elapse before a mixture of 90% carbon-11 and 10% boron-11 (by the number of atoms) converts itself into a mixture of 10% carbon-11 and 90% boron-11?

How is polarisation of light obtained by scattering of light?

Two identical parallel plate capacitors A and B are connected to a battery of V volts with the switch S closed. The switch is now opened and the free space between the plates of the capacitors is filled with a dielectric of dielectric constant K. Find the ratio of the total electrostatic energy stored in both capacitors before and after the introduction of the dielectric.

(i) Find equivalent capacitance between A and B in the combination given below. Each capacitor is of 2 µF capacitance.

(ii) If a dc source of 7 V is connected across AB, how much charge is drawn from the source and what is the energy stored in the network? 

Why is it necessary to introduce a radial magnetic field inside the coil of a galvanometer?

Can a galvanometer as such be used for measuring the current? Explain.

Two identical capacitors of 12 pF each are connected in series across a battery of 50 V. How much electrostatic energy is stored in the combination? If these were connected in parallel across the same battery, how much energy will be stored in the combination now?

Also find the charge drawn from the battery in each case.

State the underlying principle of working of a moving coil galvanometer. Write two reasons why a galvanometer can not be used as such to measure current in a given circuit. Name any two factors on which the current sensitivity of a galvanometer depends.

Three identical capacitors C₁, C₂ and C₃ of capacitance 6 μF each are connected to a 12 V battery as shown.

Find

(i) charge on each capacitor

(ii) equivalent capacitance of the network

(iii) energy stored in the network of capacitors

The muscles of a normal eye are least strained when the eye is focussed on an object

When objects at different distances are seen by the eye, which of the following remain constant?

A person A can clearly see objects between 25 cm and 200 cm. Which of the following may represent the range of clear vision for a person B having muscles stronger than A, but all other parameters of eye identical to that of A?

The focal length of a normal eye-lens is about

The distance of the eye-lens from the retina is x. For a normal eye, the maximum focal length of the eye-lens

A man wearing glasses of focal length +1 m cannot clearly see beyond 1 m

When we see an object, the image formed on the retina is
(a) real
(b) virtual
(c) erect
(d) inverted

Mark the correct options.
(a) If the far point goes ahead, the power of the divergent lens should be reduced.
(b) If the near point goes ahead, the power of the convergent lens should be reduced.
(c) If the far point is 1 m away from the eye, divergent lens should be used.
(d) If the near point is 1 m away from the eye, divergent lens should be used.

A person looks at different trees in an open space with the following details. Arrange the trees in decreasing order of their apparent sizes.

Can virtual image be formed on the retina in a seeing process?