1
WB JEE 2018
MCQ (Single Correct Answer)
+2
-0.5
Change Language
The insulated plates of a charged parallel plate capacitor (with small separation between the plates) are approaching each other due to electrostatic attraction. Assuming no other force to be operative and no radiation taking place, which of the following graphs approximately shows the variation with time (t) of the potential difference (V) between the plates?
A
WB JEE 2018 Physics - Current Electricity Question 19 English Option 1
B
WB JEE 2018 Physics - Current Electricity Question 19 English Option 2
C
WB JEE 2018 Physics - Current Electricity Question 19 English Option 3
D
WB JEE 2018 Physics - Current Electricity Question 19 English Option 4
2
WB JEE 2018
MCQ (Single Correct Answer)
+2
-0.5
Change Language
The bob of a pendulum of mass m, suspended by an inextensible string of length L as shown in the figure carries a small charge q. An infinite horizontal plane conductor with uniform surface charge density $$\sigma$$ is placed below it. What will be the time period of the pendulum for small amplitude oscillations?

WB JEE 2018 Physics - Electrostatics Question 21 English
A
$$2\pi \sqrt {{L \over {\left( {g - {{mq} \over {{\varepsilon _0}\sigma }}} \right)}}} $$
B
$$\sqrt {{L \over {\left( {g - {{mq\sigma } \over {{\varepsilon _0}}}} \right)}}} $$
C
$${1 \over {2\pi }}\sqrt {{L \over {\left( {g - {{q\sigma } \over {{\varepsilon _0}m}}} \right)}}} $$
D
$$2\pi \sqrt {{L \over {\left( {g - {{q\sigma } \over {{\varepsilon _0}m}}} \right)}}} $$
3
WB JEE 2018
MCQ (More than One Correct Answer)
+2
-0
Change Language
A non-zero current passes through the galvanometer G shown in the circuit when the key K is closed and its value does not change when the key is opened. Then, which of the following statement(s) is/are true?

WB JEE 2018 Physics - Current Electricity Question 21 English
A
the galvanometer resistance is infinite.
B
the current through the galvanometer is 40 mA.
C
After the key is closed, the current through the 200$$\Omega$$ resistor is same as the current through the 300$$\Omega$$ resister.
D
The galvanometer resistance is 150$$\Omega$$
4
WB JEE 2018
MCQ (More than One Correct Answer)
+2
-0
Change Language
WB JEE 2018 Physics - Geometrical Optics Question 11 English
A ray of light is incident on a right angled isosceles prism parallel to its base as shown in the figure. Refractive index of the material of the prism is $$\sqrt 2 $$. Then, which of the following statement(s) is/are true?
A
The reflection at P is total internal.
B
The reflection at Q is total internal.
C
The ray emerging at R is parallel to the ray incident at S.
D
Total deviation of the ray is 150$$^\circ$$.
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