1. Point charges \[+4q,-q\] and \[+4q\] are kept on the
x - axis at points \[x=0\] ,\[x=a\] and \[x=2a\] respectively, then
a) Only q is in stable equilibrium
b) None of the charges are in equilibrium
c) All the charges are in unstable equilibrium
d) All the charges are in stable equilibrium
Explanation: Force on each charge is zero. But if any of the charge is displaced, the net force starts acting on all of them.
2. Two point charges of \[20\mu C\] and \[80\mu C\] are 10 cm
apart. Where will the electric field strength be zero on the line joining the charges from \[20\mu C\] charge
a) 0.1 m.
b) 0.04m
c) 0.033m
d) 0.33m
Explanation:
3.How much kinetic energy will be gained by an \[\alpha -\] particle in going from a point at 70V to
another point at 50V
a) 40 eV
b) 40 keV
c) 40 MeV
d) 0 eV
Explanation:
4. If a charged spherical conductor of radius 10 cm has potential V at a point distant 5 cm from
its centre, then the potential at a point distant 15 cm from the centre will be
a) \[\frac{1}{3}V\]
b) \[\frac{2}{3}V\]
c) \[\frac{3}{2}V\]
d) 3 V
Explanation:
5. Two unlike charges of magnitude q are separated
by a distance 2d . The potential at a point midway
between them is
a) Zero
b) \[\frac{1}{4\pi\epsilon_{0}}\]
c) \[\frac{1}{4\pi\epsilon_{0}}.\frac{q}{d}\]
d) \[\frac{1}{4\pi\epsilon_{0}}.\frac{2q}{d^{2}}\]
Explanation:
6. What is the potential energy of the equal positive
point charges of \[1\mu C\] each held 1 m apart in air
a) \[9\times 10^{-3} J\]
b) \[9\times 10^{-3} eV\]
c) 2eV / m
d) Zero
Explanation:
7. An oil drop having charge 2e is kept stationary
between two parallel horizontal plates 2.0 cm
apart when a potential difference of 12000 volts
is applied between them. If the density of oil is
900 kg/ \[m^{3} \] , the radius of the drop will be
a) \[2.0\times 10^{-6}m\]
b) \[1.7\times 10^{-6}m\]
c) \[1.4\times 10^{-6}m\]
d) \[1.1\times 10^{-6}m\]
Explanation:
8. The ratio of momenta of an electron and an \[\alpha\] -
particle which are accelerated from rest by a
potential difference of 100 volt is
a) 1
b) \[\sqrt{\frac{2m_{e}}{m_{\alpha}}}\]
c) \[\sqrt{\frac{m_{e}}{m_{\alpha}}}\]
d) \[\sqrt{\frac{m_{e}}{2m_{\alpha}}}\]
Explanation:
9.A proton is accelerated through 50,000 V. Its
energy will increase by
a) 5000 eV
b) \[8\times 10^{-15} J\]
c) 5000 J
d) 50,000 J
Explanation:
10.When a proton is accelerated through 1V, then its
kinetic energy will be
a) 1840 eV
b) 13.6 eV
c) 1 eV
d) 0.54 eV
Explanation:
