1. Total electric flux through a certain spherical Gaussian surface with a positively charged insulator ball
inside it is known to be Φ. If the ball is replaced with a conductor ball with the same charge and the
same size in electrostatic equilibrium, how would the total flux change on that Gaussian surface?
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a. It would not change
b. The flux will decrease
c. The flux will increase
d. Not enough information
2. A positively charged ball with radius r is made of insulating material. The total electric flux inside the
ball as far as a unit distance away from the centre (a<r) is given by Φ_a while the total electric flux at
a point outside the ball b distance away from the centre (b>r) is known to be Φ_b. If the ball is
replaced with a conducting ball with the same charge and size, how would Φ_a and Φ_b change ?
(assume electrostatic equilibrium condition)
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a. Φ_a will be zero while Φ_b will not change
b. Φ_a will decrease while Φ_b will not change
c. Φ_a will decrease while Φ_b will increase
d. Φ_a will be zero while Φ_b will decrease
3. An infinitely large positively charged sheet has surface charge density σ. If a positive charged particle
is to be placed near the top of this sheet (see Figure), determine the minimum mass-to-charge ratio
(m⁄q) of the particle such that it doesn’t fall to the sheet.
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Option 1
Option 3
Impossible. The charge will always fall to the
sheet
Option 2
Option 4
4. Three different particles enter three different chambers with uniform magnetic field (see Figure).
Determine the direction of deflection experienced by the particle as they enter the chamber
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a. (i) downward, (ii)inward, (iii)no deflection
c. (i) upward, (ii)outward, (iii)upward
b. (i) upward, (ii)outward, (iii)no deflection
d. (i) upward, (ii)inward, (iii)no deflection