1
WB JEE 2016
MCQ (Single Correct Answer)
+1
-0.25
Change Language
The temperature of the water of a pond is 0$$^\circ$$C while that of the surrounding atmosphere is $$-$$20$$^\circ$$C. If the density of ice is $$\rho$$, coefficient of thermal conductivity is k and latent heat of melting is L, then the thickness Z of ice layer formed increases as a function of time t is
A
$${Z^2} = {{60k} \over {\rho L}}t$$
B
$$Z = \sqrt {{{40k} \over {\rho L}}} t$$
C
$${Z^2} = {{40k} \over {\rho L}}\sqrt t $$
D
$${Z^2} = {{40k} \over {\rho L}}t$$
2
WB JEE 2016
MCQ (Single Correct Answer)
+1
-0.25
Change Language
1000 droplets of water having 2 mm diameter each coalesce to form a single drop. Given the surface tension of water is 0.072 Nm$$-$$1. The energy loss in the process is
A
8.146 $$ \times $$ 10$$-$$4 J
B
4.4 $$ \times $$ 10$$-$$4 J
C
2.108 $$ \times $$ 10$$-$$5 J
D
4.7 $$ \times $$ 10$$-$$t J
3
WB JEE 2016
MCQ (Single Correct Answer)
+1
-0.25
Change Language
A Zener diode having break-down voltage 5.6 V is connected in reverse bias with a battery of emf 10 V and a resistance of 100 $$\Omega$$ in series. The current flowing through the Zener diode is
A
88 mA
B
0.88 mA
C
4.4 mA
D
44 mA
4
WB JEE 2016
MCQ (Single Correct Answer)
+1
-0.25
Change Language
In case of a bipolar transistor $$\beta$$ = 45. The potential drop across the collector resistance of 1 k$$\Omega$$ is 5V. The base current is approximately
A
222 $$\mu$$ A
B
55 $$\mu$$ A
C
111 $$\mu$$ A
D
45 $$\mu$$ A
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