1
JEE Main 2021 (Online) 25th February Evening Shift
+4
-1
An electron with kinetic energy K1 enters between parallel plates of a capacitor at an angle '$$\alpha$$' with the plates. It leaves the plates at angle '$$\beta$$' with kinetic energy K2. Then the ratio of kinetic energies K1 : K2 will be :
A
$${{{{\cos }^2}\beta } \over {{{\cos }^2}\alpha }}$$
B
$${{\cos \beta } \over {\cos \alpha }}$$
C
$${{{{\sin }^2}\beta } \over {{{\cos }^2}\alpha }}$$
D
$${{\cos \beta } \over {\sin \alpha }}$$
2
JEE Main 2021 (Online) 24th February Morning Shift
+4
-1
Two equal capacitors are first connected in series and then in parallel. The ratio of the equivalent capacities in the two cases will be :
A
4 : 1
B
1 : 2
C
2 : 1
D
1 : 4
3
JEE Main 2020 (Online) 6th September Morning Slot
+4
-1
For the given input voltage waveform Vin(t), the output voltage waveform V0(t), across the capacitor is correctly depicted by :
A
B
C
D
4
JEE Main 2020 (Online) 5th September Evening Slot
+4
-1
A parallel plate capacitor has plate of length 'l', width ‘w’ and separation of plates is ‘d’. It is connected to a battery of emf V. A dielectric slab of the same thickness ‘d’ and of dielectric constant k = 4 is being inserted between the plates of the capacitor. At what length of the slab inside plates, will the energy stored in the capacitor be two times the initial energy stored?
A
$${l \over 4}$$
B
$${l \over 2}$$
C
$${{2l} \over 3}$$
D
$${l \over 3}$$
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