MCQ
The purpose of cathode in cathode ray tube is ______:
- ATo emit the electrons
- BTo absorb the electrons
- CTo deflect the electrons
- DTo emit the protons
✓
Answer
- To emit the electrons
Explanation:
The heated filament transfers its heat to the cathode the cathode coated by oxides of Barium or Strantium emit electrons on heating.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
A circular coil of n turns is kept in a uniform magnetic field such that the plane of the coil is perpendicular to the field. The magnetic flux associated with the coil is now $\phi$ . Now the coil is opened and made into another circular coil of twice the radius of the previous coil and kept in the same field such that the plane of the coil is perpendicular to the field. The magnetic flux associated with this coil now is:
→If the source of light used in a Young's double slit experiment is changed from red to violet:
A charged particle moves along a circle under the action of possible constant electric and magnetic fields. Which of the following are possible?
→- $\text{E}=0,\ \text{B}=0$
- $\text{E}=0,\ \text{B}\not=0$
- $\text{E}\not=0,\ \text{B}=0$
- $\text{E}\not=0,\ \text{B}\not=0$
A convex lens forms a real image of an object for its two different positions on a screen. If height of the image in both the cases be 8 cm and 2 cm, then height of the object is
|
(a) 16 cm |
(b) 8 cm |
(c) 4 cm |
(d) 2 cm |
The focal length of a concave mirror is f and the distance from the object to the principle focus is x. The ratio of the size of the image to the size of the object is
|
(a) |
(b) |
(c) |
(d) |
If the distance between a point source and screen is doubled, then intensity of light on the screen will become
|
(a) Four times |
(b) Double |
(c) Half |
(d) One-fourth |
A photon of energy 3.4 eV is incident on a metal having work function 2 eV. The maximum K.E. of photo-electrons is equal to
|
(a) 1.4 eV |
(b) 1.7 eV |
(c) 5.4 eV |
(d) 6.8 eV |
Which of the following is not true for electromagnetic waves?
A charge is brought from a point on the equatorial plane of a dipole to its mid-point. Which of the following quantities remains constant?
Magnitude of produced magnetic field at any point inside a solenoid depends on: