Physics

The electric field at a point is
(a) Always continuous
(b) Continuous if there is no charge at that point
(c) Discontinuous only if there is a negative charge at that point (d) discontinuous if there is a charge at that point

Multiple Choice Questions

(One or More than One Correct Answer Type)

If Ф_s E . dS = 0 over a surface, then

(a) The electric field inside the surface and on it is zero
(b) The electric field inside the surface is necessarily uniform
(c) The number of flux lines entering the surface must be equal tothe number of flux lines leaving it
(d) All charges must necessarily be outside the surface

A hemisphere is uniformly charged positively. The electric field at a point on a diameter away from the centre is directed .

(a) Perpendicular to the diameter

(b) Parallel to the diameter

(c) At an angle tilted towards the diameter

(d) At an angle tilted away from the diameter

A point charge +q is placed at a distance d from an isolated conducting plane. The field at a point P on the other side of the plane is

(a) Directed perpendicular to the plane and away from the plane
(b) Directed perpendicular to the plane but towards the plane
(c) Directed radially away from the point charge
(d) Directed radially towards the point charge

A glass full of hot milk is poured on the table. It begins to cool gradually. Which of the following is correct?

(a) The rate of cooling is constant till milk attains the temperature of the surrounding

(b) The temperature of milk falls off exponentially with time

(c) While cooling, there is a flow of heat from milk to the surrounding as well as from surrounding to the milk but the net flow of heat is from milk to the surrounding and that is why it cools

(d) All three phenomenon, conduction, convection and radiation are responsible for the loss of heat from milk to the surroundings

Figure shows electric field lines in which an electric dipole P is placed as shown. Which of the following statements is correct?

(a) The dipole will not experience any force
(b) The dipole will experience a force towards right
(c) The dipole will experience a force towards left
(d) The dipole will experience a force upwards

Refer to the plot of temperature versus time (Fig) showing the changes in the state of ice on heating (not to scale) Which of the following is correct?

(a) The region AB represents ice and water in thermal equilibrium

(b) At B water starts boiling

(c) At C all the water gets converted into steam

(d) C to D represents water and steam in equilibrium at boiling point

'Gulab Jamuns' (assumed to be spherical) are to be heated in an oven. They are available in two sizes, one twice bigger (in radius) than the other. Pizzas (assumed to be discs) are also to be heated in oven. They are also in two sizes, one twice big (in radius) than the other. All four are put together to be heated to oven temperature. Choose the correct option from the following:

(a) Both size gulab jamuns will get heated in the same time

(b) Smaller gulab jamuns are heated before bigger ones

(c) Smaller pizzas are heated before bigger ones

(d) Bigger pizzas are heated before smaller ones

The electric flux through the surface

(a) In Fig. (iv) is the largest
(b) In Fig. (iii) is the least
(c) In Fig. (ii) is same as Fig. (iii) but is smaller than Fig. (iv)
(d) Is the same for all the figures