1
JEE Main 2019 (Online) 9th April Morning Slot
+4
-1
A wire of resistance R is bent to form a square ABCD as shown in the figure. The effective resistance between E and C is : (E is mid-point of arm CD)
A
$${7 \over {64}}R$$
B
$${1 \over {16}}R$$
C
R
D
$${3 \over {4}}R$$
2
JEE Main 2019 (Online) 9th April Morning Slot
+4
-1
A moving coil galvanometer has resistance 50$$\Omega$$ and it indicates full deflection at 4mA current. A voltmeter is made using this galvanometer and a 5 k$$\Omega$$ resistance. The maximum voltage, that can be measured using this voltmeter, will be close to :
A
15 V
B
10 V
C
40 V
D
20 V
3
JEE Main 2019 (Online) 8th April Evening Slot
+4
-1
In the circuit shown, a four-wire potentiometer is made of a 400 cm long wire, which extends between A and B. The resistance per unit length of the potentiometer wire is r = 0.01 $$\Omega$$/cm. If an ideal voltmeter is connected as shown with jockey J at 50 cm from end A, the expected reading of the voltmeter will be :-
A
0.25 V
B
0.20 V
C
0.50V
D
0.75 V
4
JEE Main 2019 (Online) 8th April Evening Slot
+4
-1
A cell of internal resistance r drives current through an external resistance R. The power delivered by the cell to the external resistance will be maximum when :-
A
R = 1000 r
B
R = r
C
R = 2r
D
R = 0.001 r
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