An inductor (L = 0.03 H) and a resistor (R = 0.15 kΩ) are connected in series to a battery of 15V EMF in a circuit shown. The key K1 has been kept closed for a long time. Then at t = 0, K1 is opened and key K2 is closed simultaneously. At t = 1 ms, the current in the circuit will be:
()
100 mA
67 mA
6.7 mA
6.7 mA
A red LED emits light at 0.1 watt uniformly around it. The amplitude of the electric field of the light at a distance of 1 m from the diode is:
1.73 V/m
2.45 V/m
5.48 V/m
5.48 V/m
An LCR circuit is equivalent to a damped pendulum. In an LCR circuit, the capacitor is charged to Q0 and then connected to the L and R as shown.
If a student plots graphs of the square of maximum charge ( QMax2 ) on the capacitor with time (t) for two different values L1 and L2 (L1 > L2) of L then which of the following represents this graph correctly? (Plots are schematic and not drawn to scale)
D.
Inductance is inertia of circuit. It means inductance oppose the flow of charge, more inductance means decay of charge is slow.
In option (d), in a given time to .
So, L1> L2
A signal of 5 kHz frequency is amplitude modulated on a carrier wave of frequency 2 MHz. The frequencies of the resultant signal is/are:
2005 kHz, and 1995 kHz
2005 kHz, 2000 kHz and 1995 kHz
2000 kHz and 1995 kHz
2000 kHz and 1995 kHz
Match List – I (Fundamental Experiment) with List – II (its conclusion) and select the correct option from the choices given below the list:
List I |
List II |
(A) Franck-Hertz Experiment | (i) Particle nature of light |
(B) Photo-electric experiment | (ii) Discrete energy levels of atom |
(C) Davison – Germer Experiment | (iii) Wave nature of electron |
(iv) Structure of atom |
A | B | C |
1 | 4 | 3 |
A | B | C |
2 | 4 | 3 |
A | B | C |
2 | 1 | 3 |
A | B | C |
2 | 1 | 3 |
As an electron makes a transition from an excited state to the ground state of a hydrogen – like atom/ion:
kinetic energy, potential energy and total energy decrease
kinetic energy decreases, potential energy increases but total energy remains same
kinetic energy and total energy decrease but potential energy increases
kinetic energy and total energy decrease but potential energy increases
Assuming human pupil to have a radius of 0.25 cm and a comfortable viewing distance of 25 cm, the minimum separation between two objects that human eye can resolve at 500 nm wavelength is:
1 μm
30 μm
100 μm
100 μm
On a hot summer night, the refractive index of air is smallest near the ground and increases with height from the ground. When a light beam is directed horizontally, the Huygens’ principle leads us to conclude that as it travels, the light beam:
goes horizontally without any deflection
bends downwards
bends upwards
bends upwards
A train is moving on a straight track with speed 20 ms-1 .It is blowing its whistle at the frequency of 1000 Hz. The percentage change in the frequency heard by a person standing near the track as the train passes him is (speed of sound = 320 ms-1 ) close to :
6%
12%
18%
18%
Monochromatic light is incident on a glass prism of angle A. If the refractive index of the material oft the prism is μ, a ray incident at an angle θ, on the face AB would get transmitted through the face AC of the prism provided