1
COMEDK 2024 Morning Shift
MCQ (Single Correct Answer)
+1
-0

Two metal spheres, one of radius $$\frac{R}{2}$$ and the other of radius $$2 \mathrm{R}$$ respectively have the same surface charge density They are brought in contact and separated. The ratio of their new surface charge densities is

A
$$2: 1$$
B
$$4: 1$$
C
$$1: 4$$
D
$$1: 2$$
2
COMEDK 2023 Morning Shift
MCQ (Single Correct Answer)
+1
-0

When $$10^{19}$$ electrons are removed from a neutral metal plate, the electric charge on it is

A
$$-1.6 \mathrm{~C}$$
B
$$+1.6 \mathrm{~C}$$
C
$$10^{+19} \mathrm{~C}$$
D
$$10^{-19} \mathrm{~C}$$
3
COMEDK 2023 Evening Shift
MCQ (Single Correct Answer)
+1
-0

Two point charges $$20 \mu \mathrm{C}$$ and $$-10 \mu \mathrm{C}$$ are separated by a distance of $$1 \mathrm{~m}$$ in air. At what point on the line joining the two charges, the electric potential is zero.

A
$$0.5 \mathrm{~m}$$ from the charge $$10 \mu \mathrm{C}$$
B
$$0.76 \mathrm{~m}$$ from the charge $$20 \mu \mathrm{C}$$
C
$$0.67 \mathrm{~m}$$ from the charge $$20 \mu \mathrm{C}$$
D
$$0.25 \mathrm{~m}$$ from the charge $$10 \mu \mathrm{C}$$
4
COMEDK 2023 Evening Shift
MCQ (Single Correct Answer)
+1
-0

A spherical metal ball of density '$$\rho$$' and radius '$$r$$' is immersed in a liquid of density '$$\sigma$$'. When an electric field is applied in the upward direction the metal ball remains just suspended in the liquid. Then the expression for the charge on the metal ball is :

A
$$q=\frac{\left[\frac{4}{3} \pi r^3 \rho g\right]}{\sigma E}$$
B
$$q=\frac{\left[4 \pi r^3(\rho-\sigma) g\right]}{3 E}$$
C
$$q=\frac{\left[4 \pi r^2 \rho g\right]}{\sigma E}$$
D
$$q=\frac{\left[4 \pi r^2(\rho-\sigma) g\right]}{E}$$
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