1
AIEEE 2004
+4
-1
A charge particle $$'q'$$ is shot towards another charged particle $$'Q'$$ which is fixed, with a speed $$'v'$$. It approaches $$'Q'$$ upto a closest distance $$r$$ and then returns. If $$q$$ were given a speed of $$'2v'$$ the closest distances of approaches would be
A
$$r/2$$
B
$$2r$$
C
$$r$$
D
$$r/4$$
2
AIEEE 2004
+4
-1
Four charges equal to -$$Q$$ are placed at the four corners of a square and a charge $$q$$ is at its center. If the system is in equilibrium the value of $$q$$ is
A
$$- {Q \over 2}\left( {1 + 2\sqrt 2 } \right)$$
B
$${Q \over 4}\left( {1 + 2\sqrt 2 } \right)$$
C
$$- {Q \over 4}\left( {1 + 2\sqrt 2 } \right)$$
D
$${Q \over 2}\left( {1 + 2\sqrt 2 } \right)$$
3
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
$$4.8 \times {10^{ - 18}}\,C$$
4
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
$$\left( {{\phi _1} + {\phi _2}} \right){\varepsilon _0}$$
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