Physics

A sphere, a cube and a thin circular plate, all of same material and same mass are initially heated to same high temperature.

(a) Plate will cool fastest and cube the slowest

(b) Sphere will cool fastest and cube the slowest

(c) Plate will cool fastest and sphere the slowest

(d) Cube will cool fastest and plate the slowest.

In figure two positive charges q₂ and q₃ fixed along the y-axis, exert a net electric force in the +x-direction on a charge q₁, fixed along the x-axis. If a positive charge Q is added at (x, 0), the force on q₁

(a) Shall increase along the positive x-axis
(b) Shall decrease along the positive x-axis
(c) Shall point along the negative x-axis
(d) Shall increase but the direction changes because of the intersection of Q with q₂ and q₃

The radius of a metal sphere at room temperature T is R, and the coefficient of linear expansion of the metal is α. The sphere is heated a little by a temperature ?T so that its new temperature is T+ ?T. The increase in the volume of the sphere is approximately

(a) 2παR?T

(b) πR²α?T

(c) 4πR³?T/3

(d) 4παR³ $\mathit{\alpha }$ ?T

Figure shows the electric field lines around three point charges A, B and C.

(i) Which charges are positive?
(ii) Which charge has the largest magnitude? Why?
(iii) In which region or regions of the picture could the electric field be zero? Justify your answer.
(a) Near A (b) Near B
(c) Near C (d) Nowhere

Heat is associated with

(a) Kinetic energy of random motion of molecules

(b) Kinetic energy of orderly motion of molecules

(c) Total kinetic energy of random and orderly motion of molecules

(d) Kinetic energy of random motion in some cases and kinetic energy of orderly motion in other

As the temperature is increased, the time period of a pendulum

(a) Increases as its effective length increases even though its centre of mass still remains at the centre of the bob

(b) Decreases as its effective length increases even though its centre of mass still remains at the centre of the bob

(c) Increases as its effective length increases due to shifting of centre of mass below the centre of the bob

(d) Decreases as its effective length remains same but the centre of mass shifts above the centre of the bob

Two charges q and -3q are placed fixed on x-axis separated by distance d. where should a third charge 2q be placed such that it will not experience any force?

An aluminium sphere is dipped into water. Which of the following is true?

(a) Buoyancy will be less in water at 0°C than that in water at 4°C.

(b) Buoyancy will be more in water at 0°C than that in water at 4°C.

(c) Buoyancy in water at 0°C will be same as that in water at 4°C.

(d) Buoyancy may be more or less in water at 4°C depending on the radius of the sphere.

Figure represents a crystal unit of cesium chloride, CsCl. The cesium atohis, represented by open circles are situated at the comers of a cube of side 0.40 nm, whereas a Cl atom is situated at
the centre of the Cube. The Cs atoms are deficient in one electron while the Cl atom carries an excess electron.

(i) What is the net electric field on the Cl atom due to eight Cs atoms?
(ii) Suppose that the Cs atom at the comer A is missing. What is the net force now on the Cl atom due to seven remaining Cs atoms?

The graph between two temperature scales A and B is shown in Fig. Between upper fixed point and lower fixed point there are 150 equal division on scale A and 100 on scale B. The relationship for conversion between the two scales is given by

(a) $\frac{{\mathit{t}}_{\mathit{A}}-180}{100}=\frac{{\mathit{t}}_{\mathit{B}}}{150}$

(b) $\frac{{\mathit{t}}_{\mathit{A}}-30}{150}=\frac{{\mathit{t}}_{\mathit{B}}}{100}$

(c) $\frac{{\mathit{t}}_{\mathit{B}}-180}{150}=\frac{{\mathit{t}}_{\mathit{A}}}{100}$

(d) $\frac{{\mathit{t}}_B-40}{100}=\frac{{\mathit{t}}_{\mathit{A}}}{180}$