1
WB JEE 2020
MCQ (Single Correct Answer)
+2
-0.5
Change Language
A conducting circular loop of resistance 20$$\Omega $$ and cross-sectional area 20 $$ \times $$ 10-2 m2 is placed perpendicular to a spatially uniform magnetic field B, which varies with time t as B = 2sin(50$$\pi $$t) T. Find the net charge flowing through the loop in 20 ms starting from t = 0.
A
0.5 C
B
0.2 C
C
0 C
D
0.14 C
2
WB JEE 2020
MCQ (Single Correct Answer)
+2
-0.5
Change Language
A pair of parallel metal plates are kept with a separation d. One plate is at a potential + V and the other is at ground potential. A narrow beam of electrons enters the space between the plates with a velocity v0 and in a direction parallel to the plates. What will be the angle of the beam with the plates after it travels an axial distance L?
A
$${\tan ^{ - 1}}\left( {{{eVL} \over {md{v_0}}}} \right)$$
B
$${\tan ^{ - 1}}\left( {{{eVL} \over {mdv_0^2}}} \right)$$
C
$${\sin ^{ - 1}}\left( {{{eVL} \over {md{v_0}}}} \right)$$
D
$${\cos ^{ - 1}}\left( {{{eVL} \over {mdv_0^2}}} \right)$$
3
WB JEE 2020
MCQ (Single Correct Answer)
+2
-0.5
Change Language
A metallic block of mass 20 kg is dragged with a uniform velocity of 0.5 ms-1 on a horizontal table for 2.1 s. The coefficient of static friction between the block and the table is 0.10. What will be the maximum possible rise in temperature of the metal block, if the specific heat of the block is 0.1 CGS unit? Assume g = 10 ms-2 and uniform rise in temperature throughout the whole block. [Ignore absorption of heat by the table]
A
0.0025$$^\circ $$ C
B
0.025$$^\circ $$ C
C
0.001$$^\circ $$ C
D
0.05$$^\circ $$ C
4
WB JEE 2020
MCQ (Single Correct Answer)
+2
-0.5
Change Language
Consider an engine that absorbs 130 cal of heat from a hot reservoir and delivers 30 cal heat to a cold reservoir in each cycle. The engine also consumes 2 J energy in each cycle to overcome friction. If the engine works at 90 cycles per minute, what will be the maximum power delivered to the load? [Assume the thermal equivalent of heat is 4.2 J/cal]
A
816 W
B
819 W
C
627 W
D
630 W
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