1
WB JEE 2021
+2
-0.5
Two metal wires of identical dimensions are connected in series. If $$\sigma$$1 and $$\sigma$$2 are the electrical conductivities of the metal wires respectively, the effective conductivity of the combination is
A
$$\sigma$$1 + $$\sigma$$2
B
$${{{\sigma _1}{\sigma _2}} \over {{\sigma _1} + {\sigma _2}}}$$
C
$${{2{\sigma _1}{\sigma _2}} \over {{\sigma _1} + {\sigma _2}}}$$
D
$${{{\sigma _1} + {\sigma _2}} \over {2{\sigma _1}{\sigma _2}}}$$
2
WB JEE 2020
+1
-0.25
A galvanometer can be converted to a voltmeter of full scale deflection V0 by connecting a series resistance R1 and can be converted to an ammeter of full scale deflection I0 by connecting a shunt resistance R2. What is the current flowing through the galvanometer at its full scale deflection?
A
$${{{V_0} - {I_0}{R_2}} \over {{R_1} - {R_2}}}$$
B
$${{{V_0} + {I_0}{R_2}} \over {{R_1} + {R_2}}}$$
C
$${{{V_0} - {I_0}{R_1}} \over {{R_2} - {R_1}}}$$
D
$${{{V_0} + {I_0}{R_1}} \over {{R_1} + {R_2}}}$$
3
WB JEE 2020
+1
-0.25

What will be the equivalent resistance between the terminals A and B of the infinite resistive network shown in the figure?
A
$${{\left( {\sqrt 3 + 1} \right)R} \over 2}$$
B
$${{\left( {\sqrt 3 - 1} \right)R} \over 2}$$
C
$$3{R \over 2}$$
D
$${\left( {\sqrt 3 + 1} \right)R}$$
4
WB JEE 2020
+1
-0.25
Consider the circuit shown.

If all the cells have negligible internal resistance, what will be the current through the 2$$\Omega$$ resistor when steady state is reached?
A
0.66 A
B
0.29 A
C
0 A
D
0.14 A
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