1
JEE Main 2021 (Online) 16th March Morning Shift
+4
-1
A conducting wire of length 'l', area of cross-section A and electric resistivity $$\rho$$ is connected between the terminals of a battery. A potential difference V is developed between its ends, causing an electric current.

If the length of the wire of the same material is doubled and the area of cross-section is halved, the resultant current would be :
A
$$4{{VA} \over {\rho l}}$$
B
$${3 \over 4}{{VA} \over {\rho l}}$$
C
$${1 \over 4}{{VA} \over {\rho l}}$$
D
$${1 \over 4}{{\rho l} \over {VA}}$$
2
JEE Main 2021 (Online) 26th February Evening Shift
+4
-1
A wire of 1$$\Omega$$ has a length of 1 m. It is stretched till its length increases by 25%. The percentage change in resistance to the nearest integer is :
A
76%
B
12.5%
C
25%
D
56%
3
JEE Main 2021 (Online) 26th February Morning Shift
+4
-1
Five equal resistances are connected in a network as shown in figure. The net resistance between the points A and B is :

A
$${{3R} \over 2}$$
B
$${{R} \over 2}$$
C
2R
D
R
4
JEE Main 2021 (Online) 24th February Morning Slot
+4
-1
A current through a wire depends on time as

i = $$\alpha$$0t + $$\beta$$t2

where $$\alpha$$0 = 20 A/s and $$\beta$$ = 8 As$$-$$2. Find the charge crossed through a section of the wire in 15 s.
A
2250 C
B
2100 C
C
260 C
D
11250 C
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Optics
Modern Physics
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