A charged particle of mass \(m\) and charge \(q\) is released from rest in an electric field of constant magnitude \(E.\) The kinetic energy of the particle after time \(t\) is:
1. \(\dfrac{2E^2t^2}{mq}\)
2. \(\dfrac{E^2q^2t^2}{2m}\)     
3. \(\dfrac{Eq^2m}{2t^2}\)
4. \(\dfrac{Eqm}{2t}\)
Subtopic:  Electric Field |
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An electron having charge \(e\) and mass \(m\) is moving in a uniform electric field \(E.\) Its acceleration will be:
1. \(\dfrac{e^2}{m}\)
2. \(\dfrac{E^2e}{m}\)
3. \(\dfrac{eE}{m}\)
4. \(\dfrac{mE}{e}\)

Subtopic:  Electric Field |
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AIIMS - 2002
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\(ABC\) is an equilateral triangle. Charges \(+q\)  are placed at each corner. The electric intensity at \(O\) will be: 

       

1. \(\dfrac{1}{4\pi\epsilon _0}\dfrac{q}{r^{2}}\) 2. \(\dfrac{1}{4\pi\epsilon _0}\dfrac{q}{r^{}}\)
3. zero 4. \(\dfrac{1}{4\pi\epsilon _0}\dfrac{3q}{r^{2}}\)
Subtopic:  Electric Field |
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PMT - 1985
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A ring of radius \(r\) contains a charge \(q\) distributed uniformly over its length. What is the electric field at the centre of the ring?
1. \(\dfrac{q}{(4\pi\varepsilon_0r^2)}\)
2. \(\dfrac{q}{(4\pi\varepsilon_0r)}\)
3. zero
4. \(\dfrac{q}{(4\pi\varepsilon_0r^3)}\)
Subtopic:  Electric Field |
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A vertical electric field of magnitude \(4.9\times 10^{5}\) N/C just prevents a water droplet of a mass of \(0.1\) g from falling. The value of charge on the droplet will be: (Given \(g = 9.8\) m/s2 )
1. \(1.6\times 10^{-9}\) C
2. \(2.0\times 10^{-9}\) C
3. \(3.2\times 10^{-9}\) C
4. \(0.5\times10^{-9}\) C
Subtopic:  Electric Field |
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JEE
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Two equal and opposite charges of masses \({m_1}\) and \({m_2}\) are accelerated in a uniform electric field through the same distance. What is the ratio of their accelerations if their ratio of masses is \(\dfrac{m_{1}}{m_{2}}=0.5?\)
1. \(\dfrac{{a}_{1}}{{a}_{2}}=2\)

2. \(\dfrac{{a}_{1}}{{a}_{2}}=0.5\)

3. \(\dfrac{{a}_{1}}{{a}_{2}}=3\)

4. \(\dfrac{a_{1}}{a_{2}}=1\)
Subtopic:  Electric Field |
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The electric field inside a uniformly charged thin spherical shell having radius \(R\) and total charge \(Q\) is:
(\( \varepsilon_0\) is the permittivity of free space)
1. \(\frac{Q}{4\pi \varepsilon_0R^2}\) 2. \(\frac{Q}{4\pi \varepsilon_0R}\)
3. zero 4. \(\frac{Q}{2\pi \varepsilon_0R^2}\)
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Two thin insulating sheets (each having charge density \(+\sigma \)) are arranged as shown. The net electric field magnitude in the three regions will be respectively:
                 
1. \({E}_{1}\;{=}\;\dfrac{\mathit{\sigma}}{{\mathit{\epsilon}}_{0}}{;}\;{E}_{2}\;{=}\;{0}{;}\;{E}_{3}\;{=}\;\dfrac{\mathit{\sigma}}{{\mathit{\epsilon}}_{0}}~\)
2. \({E}_{1}\;{=}\;{E}_{2}\;{=}\;{E}_{3}\;{=}\;{0} \)
3. \({E}_{1}\;{=}\;{0}{;}\;{E}_{2}\;{=}\;\dfrac{\mathit{\sigma}}{2{\mathit{\epsilon}}_{0}}{;}\;{E}_{3}\;{=}\;\dfrac{\mathit{\sigma}}{{\mathit{\epsilon}}_{0}}~~\)
4. \({E}_{1}\;{=}\;\dfrac{\mathit{\sigma}}{{\mathit{\epsilon}}_{0}}{;}\;{E}_{2}\;{=}\;{0}{;}\;{E}_{3}\;{=}\;\dfrac{\mathit{\sigma}}{2{\mathit{\epsilon}}_{0}}\)
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A metallic solid sphere is placed in a uniform electric field. The lines of force follow the path(s) shown in the figure as:

           
1. \(1\)
2. \(2\)
3. \(3\)
4. \(4\)

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A cube of side a has a charge \(q\) at each of its vertices. The net electric field intensity at its centre is: 
(\(r\) is the distance between a corner and the centre, and \(k=1/4\pi \varepsilon_0\) )
1. zero
2. \(kq/r^2\)
3. \(12kq/r^2\)
4. \(6kq/r^2\)

Subtopic:  Electric Field |
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