MCQ
Why is gold used in the Gold-leaf electroscope?
  • A
    Gold is easily available in nature.
  • B
    Gold is malleable.
  • C
    Gold is conducting in nature.
  • D
    Gold is cheap.

Answer

  1. Gold is malleable.

Explanation:

Though gold is a costly metal it is used in electroscope because of the property malleability. This means very thin and light sheets can be formed from gold simply by hammering or rolling and hence the deflection of the light gold plates increases.

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

Which is the frequency range of gamma rays from the following?

The current carrying wire and the rod AB are in the same plane. The rod moves parallel to the wire with a velocity v. Which one of the following statements is true about induced emf in the rod

(a) End A will be at lower potential with respect to B

(b) A and B will be at the same potential

(c) There will be no induced e.m.f. in the rod

(d) Potential at A will be higher than that at B

A coil having an area  is placed in a magnetic field which changes from  to   in a interval of 2 second. The e.m.f. induced in the coil will be

(a)  4 V

(b) 3 V

(c)  1.5 V 

(d) 2 V

In a plano-convex lens the radius of curvature of the convex lens is 10 cm.  If the plane side is polished, then the focal length will be (Refractive index = 1.5)

(a) 10.5 cm

(b) 10 cm

(c) 5.5 cm

(d) 5 cm

Which of the following is wrong statement about binding energy?
A proton, a deuteron and an α particle are accelerated through same potential difference and then they enter in a normal uniform magnetic field, the ratio of their kinetic energies will be:
In Young's double-slit experiments, a monochromatic light source is used. The shape of interference fringes produced on screen will be :

The light of wavelength 6328 Å is incident on a slit of width 0.2 mm perpendicularly, the angular width of central maxima will be

(a) 0.36°

(b) 0.18 °

(c) 0.72°  

(d) 0.09°

Electrons are emitted by a hot filament and are accelerated by an electric field, as shown in the figure. The two stops at the left ensure that the electron beam has a uniform cross-section.

  1. The speed of the electrons is more at B than at A.
  2. The electric current is from left to right.
  3. The magnitude of the current is larger at B than at A.
  4. The current density is more at B than at A.

Which of the following statement is not correct

(a) Photographic plates are sensitive to infrared rays

(b) Photographic plates are sensitive to ultraviolet rays

(c) Infra-red rays are invisible but can cast shadows like visible light

(d) Infrared photons have more energy than photons of visible light