A force acts on a 2 kg object so that its position is given as a function of time as x = 3t2 + 5. What is the work done by this force in first 5 seconds ?

A block of mass m, lying on a smooth horizontal surface, is attached to a sring (of negligible mass) of spring constant k. The other end of the spring is fixed, as shown in the figure. The block is initially at rest in its equilibrium position. If now the block is pulled with a constant force F, the maximum speed of the block is :

In the figure shown, a circuit contains two identical resistors with resistance R = 5$$\Omega$$ and an inductance with L = 2mH. An ideal battery of 15 V is connected in the circuit. What will be the current through the battery long after the switch is closed ?

Consider the LR circuit shown in the figure. If the switch S is closed at t = 0 then the amount of charge that passes through the battery between t = 0 and t = {L \over R} is :

A coil of self inductance 10 mH and resistance 0.1 $$\Omega$$ is connected through a switch to a battery of internal resistance 0.9 $$\Omega$$. After the switch is closed, the time taken for the current to attain 80% of the saturation value is: [take ln 5 = 1.6]

A transformer consisting of 300 turns in the primary and 150 turns in the secondary gives output power of 2.2 kW. If the current in the secondary coil is 10A, then the input voltage and current in the primary coil are :

A circuit connected to an ac source of emf e = e0sin(100t) with t in seconds, gives a phase difference of $$\pi$$/4 between the emf e and current i. Which of the following circuits will exhibit this ?

An alternating voltage v(t) = 220 sin 100 $$\pi$$t volt is applied to a purely resistance load of 50$$\Omega$$ . The time taken for the current to rise from half of the peak value to the peak value is :

In the above circuit, C = {{\sqrt 3 } \over 2}$$\mu$$F, R2 = 20 $$\Omega$$, L = {{\sqrt 3 } \over {10}} H and R1 = 10 $$\Omega$$. Current in L-R1 path is I1 and in C-R2 path it is I2 . The voltage of A.C. source is given by, V = 200 $$\sqrt{2}$$ sin (100 t) volts . The phase difference between I1 and I2 is :

In the circuit shown, the switch S1 is closed at time t = 0 and the switch S2 is kept open. At some later time(t0), the switch S1 is opened and S2 is closed. The behavior of the current I as a function of time 't' is given by :

A series AC circuit containing an inductor (20 mH), a capacitor (120 $$\mu$$F) and a resistor (60 $$\Omega$$) is driven by an AC source of 24V/50 Hz. The energy dissipated in the circuit in 60 s is :

A power transmission line feeds input power at 2300 V to a srep down transformer with its primary windings having 4000 turns. The output power is delivered at 230 V by the transformer. If the current in the primary of the transformer is 5A and its efficiency is 90%, the output current would be :

Given below in the the left column are different modes of communication using the kinds of waves given the right column. .tg {border-collapse:collapse;border-spacing:0;width: 100%} .tg td{font-family:Arial, sans-serif;font-size:14px;padding:10px 5px;border-style:solid;border-width:1px;overflow:hidden;word-break:normal;border-color:black;} .tg th{font-family:Arial, sans-serif;font-size:14px;font-weight:normal;padding:10px 5px;border-style:solid;border-width:1px;overflow:hidden;word-break:normal;border-color:black;} .tg .tg-hgcj{font-weight:bold;text-align:center} .tg .tg-s268{text-align:left} .tg .tg-xk68{font-weight:bold;color:#fe0000;text-align:center} .tg .tg-0lax{text-align:left;vertical-align:top} A Optical Fibre communication P Ultrasound B Radar Q Infrared Light C Sonar R Microwaves D Mobile Phones S Radio Waves

In an amplitude modulator circuit, the carrier wave is given by, C(t) = 4 sin(20000 $$\pi$$t) while modulating signal is given by, m(t) = 2 sin (2000 $$\pi$$t). The values of modulation index and lower side band frequency are :

A message signal of frequency 100 MHz and peak voltage 100 V is used to execute amplitude modulation on a carrier wave of frequency 300 GHz and peak voltage 400 V. The modulation index and difference between the two side band frequencies are :

The physical sizes of the transmitter and receiver antenna in a communication system are :-

A signal Acoswt is transmitted using v0 sin $$\omega$$0t as carrier wave. The correct amplitude modulated (AM) signal is

In a line of sight radio communication, a distance of about 50 km is kept between the transmitting and receiving antennas. If the height of the receiving antenna is 70m, then the minimum height of the transmitting antenna should be : (Radius of the Earth = 6.4 × 106 m).

The wavelength of the carrier waves in a modern optical fiber communication network is close to :

A 100 V carrier wave is made to vary between 160 V and 40 V by a modulating signal. What is the modulation index ?