In the electron microscope, electric & magnetic fields are used as_______________?

Related Mcqs:

1. When an electron moving with a uniform speed in a vacuum enters a magnetic field in a direction perpendicular to the field the subsequent path of the electron is ___________________?

   A. a straight line parallel to the field
   B. a parabola in a plane perpendicular to the field
   C. a circle in a plane perpendicular to the field
   D. a straight line along its initial direction

2. Which of the following are not deflected by electric and magnetic fields ?

   A. Alpha rays
   B. Beta rays
   C. Gamma rays
   D. None of these

   Submitted by: Aamir Balouch

3. An electron enters a region where the electric field E is perpendicular to the magnetic field B. It will suffer no deflection if_________________?

   A. E = BeV
   B. B = eE/V
   C. E = BV
   D. E = BeV/2

4. In an electron microscope, we use energetic particles because of______________?

   A. Penetrating power is high
   B. Kinetic energy is large
   C. Wavelength is very short
   D. All the above reasons

5. For confinement of electron in a box of radius 10-14m the electron, speed should be_____________?

   A. 107m/sec
   B. Should be greater than the speed of light.
   C. Be zero
   D. Not be wave-like

6. Very weak magnetic fields are detected by___________________?

   A. Squids
   B. Magnetic resonance imaging (MRI)
   C. Magnetometer
   D. Oscilloscope

7. In bringing an electron towards the second electron, the electrostatic potential energy of the system

   A. Decreases
   B. increases
   C. remains the same
   D. becomes zero

   Submitted by: Tauseef Ali

8. The electric P.E of an electron in an orbit at a distance rn from the positive charge_____________?

   A. Ke2/rn
   B. Ke2/rn2
   C. ÀKe2/rn
   D. ÀKe2/rn2

9. A current carrying conductor is placed in a uniform magnetic field parallel to it. The magnetic force experienced by the conductor is _____________________?

   A. F=1/B
   B. F=1/Bsinθ
   C. F/0
   D. F=1/Bcosθ

10. If the plane of the rectangular coil is parallel to the magnetic field (i.e radial magnetic field) the torque on the coil is_____________________?

    A. τ = NIAB cosφ
    B. τ = NIAB sinφ
    C. τ = NIAB tanφ
    D. τ = NIAB