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

The temperatures of the junctions of a bismuth-silver thermocouple are maintained at 0°C and 0.001°C. Find the thermo-emf (Seebeck emf) developed. For bismuth-silver, a = − 46 × 10⁻⁶ V°C⁻¹ and b = −0.48 × 10⁻⁶ V°C⁻².

A plate of area 10 cm² is to be electroplated with copper (density 9000 kg m⁻³) to a thickness of 10 micrometres on both sides, using a cell of 12 V. Calculate the energy spent by the cell in the process of deposition. If this energy is used to heat 100 g of water, calculate the rise in the temperature of the water. ECE of copper = 3 × 10⁻⁷ kg C⁻¹and specific heat capacity of water = 4200 J kg⁻¹.

When a boron nucleus `(""_5^10"B")` is bombarded by a neutron, a α-particle is emitted. Which nucleus will be formed as a result?

The graph of ln `("R"/"R"_0)` versus ln A (R = radius of a nucleus and A = its mass number) is ______.

Two lithium nuclei in a lithium vapour at room temperature do not combine to form a carbon nucleus because

Electric charges are distributed in a small volume. The flux of the electric field through a spherical surface of radius 10 cm surrounding the total charge is 25 V m. The flux over a concentric sphere of radius 20 cm will be _____________ .

Drive the expression for electric field at a point on the equatorial line of an electric dipole.

Depict the orientation of the dipole in (i) stable, (ii) unstable equilibrium in a uniform electric field.

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.

Derive the expression for the electric potential due to an electric dipole at a point on its axial line.

Depict the equipotential surfaces due to an electric dipole. 

(i)Obtain the expression for the torque `vecτ` experienced by an electric dipole of dipole moment `vecP` in a uniform electric field, `vecE` .

(ii) What will happen if the field were not uniform?

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.

A normal eye is not able to see objects closer than 25 cm because

A thin converging lens is formed with one surface convex and the other plane. Does the position of image depend on whether the convex surface or the plane surface faces the object?

A double convex lens has two surfaces of equal radii R and refractive index \[m = 1 \cdot 5\]

A symmetric double convex lens in cut in two equal parts by a plane perpendicular to the principal axis. If the power of the original lens was 4 D, the power a cut-lens will be

A symmetric double convex lens is cut in two equal parts by a plane containing the principal axis. If the power of the original lens was 4 D, the power of a divided lens will be

Consider three converging lenses L₁, L₂ and L₃ having identical geometrical construction. The index of refraction of L₁ and L₂ are \[\mu_1   \text{ and }   \mu_2\] respectively. The upper half of the lens L₃ has a refractive index \[\mu_1\] and the lower half has \[\mu_2\]  following figure . A point object O is imaged at O₁ by the lens L₁ and at O₂ by the lens L₂placed in same position. If L₃ is placed at the same place,

(a) there will be an image at O₁
(b) there will be an image at O₂.
(c) the only image will form somewhere between O₁ and O₂
(d) the only image will form away from O₂.