1
JEE Main 2022 (Online) 29th July Morning Shift
+4
-1

Two metallic wires of identical dimensions are connected in series. If $$\sigma_{1}$$ and $$\sigma_{2}$$ are the conductivities of the these wires respectively, the effective conductivity of the combination is :

A
$$\frac{\sigma_{1} \sigma_{2}}{\sigma_{1}+\sigma_{2}}$$
B
$$\frac{2 \sigma_{1} \sigma_{2}}{\sigma_{1}+\sigma_{2}}$$
C
$$\frac{\sigma_{1}+\sigma_{2}}{2 \sigma_{1} \sigma_{2}}$$
D
$$\frac{\sigma_{1}+\sigma_{2}}{\sigma_{1} \sigma_{2}}$$
2
JEE Main 2022 (Online) 28th July Evening Shift
+4
-1

Given below are two statements :

Statement I : A uniform wire of resistance $$80 \,\Omega$$ is cut into four equal parts. These parts are now connected in parallel. The equivalent resistance of the combination will be $$5 \,\Omega$$.

Statement II: Two resistances 2R and 3R are connected in parallel in a electric circuit. The value of thermal energy developed in 3R and 2R will be in the ratio $$3: 2$$.

In the light of the above statements, choose the most appropriate answer from the option given below

A
Both statement I and statement II are correct
B
Both statement I and statement II are incorrect
C
Statement I is correct but statement II is incorrect
D
Statement I is incorrect but statement II is correct
3
JEE Main 2022 (Online) 28th July Morning Shift
+4
-1

A wire of resistance R1 is drawn out so that its length is increased by twice of its original length. The ratio of new resistance to original resistance is :

A
9 : 1
B
1 : 9
C
4 : 1
D
3 : 1
4
JEE Main 2022 (Online) 27th July Evening Shift
+4
-1

(A) The drift velocity of electrons decreases with the increase in the temperature of conductor.

(B) The drift velocity is inversely proportional to the area of cross-section of given conductor.

(C) The drift velocity does not depend on the applied potential difference to the conductor.

(D) The drift velocity of electron is inversely proportional to the length of the conductor.

(E) The drift velocity increases with the increase in the temperature of conductor.

Choose the correct answer from the options given below :

A
(A) and (B) only
B
(A) and (D) only
C
(B) and (E) only
D
(B) and (C) only
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