1
AIEEE 2004
+4
-1
A charged oil drop is suspended in a uniform field of $$3 \times {10^4}$$ $$v/m$$ so that it neither falls nor rises. The charge on the drop will be (Take the mass of the charge $$= 9.9 \times {10^{ - 15}}\,\,kg$$ and $$g = 10\,m/{s^2}$$)
A
$$1.6 \times {10^{ - 18}}\,C$$
B
$$3.2 \times {10^{ - 18}}\,C$$
C
$$3.3 \times {10^{ - 18}}\,C$$
D
$$4.8 \times {10^{ - 18}}\,C$$
2
AIEEE 2003
+4
-1
If the electric flux entering and leaving an enclosed surface respectively is $${\phi _1}$$ and $${\phi _2},$$ the electric charge inside the surface will be
A
$$\left( {{\phi _2} - {\phi _1}} \right){\varepsilon _0}$$
B
$$\left( {{\phi _2} + {\phi _1}} \right)/{\varepsilon _0}$$
C
$$\left( {{\phi _2} - {\phi _1}} \right)/{\varepsilon _0}$$
D
$$\left( {{\phi _1} + {\phi _2}} \right){\varepsilon _0}$$
3
AIEEE 2003
+4
-1
A thin spherical conducting shell of radius $$R$$ has a charge $$q.$$ Another charge $$Q$$ is placed at the center of the shell. The electrostatic potential at a point $$P$$ a distance $${R \over 2}$$ from the center of the shell is
A
$${{2Q} \over {4\pi {\varepsilon _0}R}}$$
B
$${{2Q} \over {4\pi {\varepsilon _0}R}} - {{2q} \over {4\pi {\varepsilon _0}R}}$$
C
$${{2Q} \over {4\pi {\varepsilon _0}R}} + {q \over {4\pi {\varepsilon _0}R}}$$
D
$${{\left( {q + Q} \right)2} \over {4\pi {\varepsilon _0}R}}$$
4
AIEEE 2003
+4
-1
Three charges $$- {q_1}, + {q_2}$$ and $$- {q_3}$$ are placed as shown in the figure. The $$x$$-component of the force on $$- {q_1}$$ is proportional to
A
$${{{q_2}} \over {{b^2}}} - {{{q_3}} \over {{a^2}}}\cos \theta$$
B
$${{{q_2}} \over {{b^2}}} + {{{q_3}} \over {{a^2}}}\sin \theta$$
C
$${{{q_2}} \over {{b^2}}} + {{{q_3}} \over {{a^2}}}\cos \theta$$
D
$${{{q_2}} \over {{b^2}}} - {{{q_3}} \over {{a^2}}}sin\theta$$
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