Question
How will the thermionic current vary if the filament current is increased?

Answer

If the filament current is increased, it will increase the temperature of the cathode (metal) and the cathode will emit more electrons. This will lead to an increase in the number of thermions emitted per unit time. As a result, the thermionic current will increase.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

Find the ratio of the volume of oxygen molecules and the total volume occupied by them at STP. Take the diameter of an oxygen molecule as 3Å.
Read the passage given below and answer the following questions from 1 to 5.
Relative velocity is velocity of any object with respect to other object which may be stationary or moving. Consider two objects A and B moving uniformly with average velocities vA and vB in one dimension, say along x-axis. (Unless otherwise specified, the velocities mentioned in this chapter are measured with reference to the ground). If xA (0) and xB (0) are positions of objects A and B, respectively at time t = 0, their positions xA (t) and xB (t) at time t are given by
xA (t) = xA (0) + vA t
xB (t) = xB (0) + vB t
Then, the displacement from object A to object B is given by
xBA(t) = xB (t) – xA (t)
= [xB (0) – xA (0) ] + (vB – vA) t.
It tells us that as seen from object A, object B has a velocity vB – vA because the displacement from A to B changes steadily by the amount vB – vA in each unit of time. We say that the velocity of object B relative to object A is vB – vA
VBA = vB – vA
Similarly, velocity of object A relative to object B is:
VAB = vA – vB
This shows VBA= – VAB.
  1. Velocity of object A relative to object B is:
  1. VAB = vA – vB
  2. VBA = vB – vA
  3. None of these
  1. Velocity of object B relative to object A is:
  1. vB – vA
  2. vA – vB
  3. None of these
  1. What is relative velocity?
  1. What is relative displacement?
  1. Show that VBA = – VAB :
Indian style of cooling drinking water is to keep it in a pitcher having porous walls. Water comes to the outer surface very slowly and evaporates. Most of energy needed for evaporation is taken from the water itself and the water is cooled down. Assume that a pitcher contains 10kg of water and 0.2g of water comes out per second. Assuming no backward heat transfer from the atmosphere to the water, calculate the time in which the temperature decrease by 5°C. Specific heat capacity of water = 4200J kg-1°C-1 and latent heat of vaporization of water = 2.27 × 106 J kg-1.
A magnetic dipole of magnetic moment $0.72\sqrt{2}\text{ A-m}^2$ -is placed horizontally with the north pole pointing towards east. Find the position of the neutral point if the horizontal component of the earth's magnetic field is $18\mu\text{T.}$
A ladder is resting with one end on a vertical wall and the other end on a horizontal floor. Is it more likely to slip when a man stands near the bottom or near the top?
After a good meal at a party you wash your hands and find that you have forgotten to bring your handkerchief. You shake your hands vigorously to remove the water as much as you can. Why is water removed in this process?
In one of the exercises to strengthen the wrist and fingers, a person squeezes and releases a soft rubber ball. Is the work done on the ball positive, negative or zero during compression? During expansion?
A short magnet oscillates in an oscillation magnetometern with a time period of 0.10s where the earth's horizontal magnetic field is $24\mu\text{T}.$ A downward current of 18 A is established in a vertical wire placed 20cm east of the magnet. Find the new time period.
Read the passage given below and answer the following questions from 1 to 5.

PE of Spring

There are many types of spring. Important among these are helical and spiral springs as shown in figure.

Usually, we assume that the springs are massless. Therefore, work done is stored in the spring in the form of elastic potential energy of the spring. Thus, potential energy of a spring is the energy associated with the state of compression or expansion of an elastic spring.

 

  1. The potential energy of a body is increases in which of the following cases?
  1. If work is done by conservative force
  2. If work is done against conservative force
  3. If work is done by non-conservative force
  4. If work is done against non- conservative force
  1. The potential energy, i.e. U (x) can be assumed zero when:
  1. x = 0
  2. gravitational force is constant
  3. infinite distance from the gravitational source
  4. All of the above
  1. The ratio of spring constants of two springs is 2 : 3. What is the ratio of their potential energy, if they are stretched by the same force?
  1. 2 : 3
  2. 3 : 2
  3. 4 : 9
  4. 9 : 4
  1. The potential energy of a spring increases by 15 J when stretched by 3cm. If it is stretched by 4cm, the increase in potential energy is:
  1. 27 J
  2. 30 J
  3. 33 J
  4. 36 J
  1. The potential energy of a spring when stretched through a distance x is 10 J. What is the amount of work done on the same spring to stretch it through an additional distance x?
  1. 10 J
  2. 20 J
  3. 30 J
  4. 40 J