Recent questions tagged exemplar

A $220\;V$ A.C supply in connected between points A and B as shown in the figure . What will be the potential difference V across the capacitor ?

asked Dec 31, 2016 by meena.p

1 answer

The conductivity of a semiconductor increases with increases in temperature because:

asked Dec 31, 2016 by meena.p

1 answer

In the circuit given below , when the input voltage of the base resistance is $10\;V,V_{BE}$ is zero. and $V_{CE}$ is also zero. Find the value of $I_c$ and $\beta$

asked Dec 31, 2016 by meena.p

1 answer

In the circuit given below , when the input voltage of the base resistance is $10\;V,V_{BE}$ is zero. and $V_{CE}$ is also zero. Find the value of $I_b$

asked Dec 31, 2016 by meena.p

1 answer

A rectangular loop of wire ABCD is kept close to an infinitely long wire carrying a current $ I (t) = I_0 (1 - \frac {t}{T}) for $ 0 \leq t \leq T$ and $ I (0) = 0$ for t > T, as shown in the fig. Find the total charge passing through a given point in the loop, in time T, The resistance of the loop is R.

asked Dec 30, 2016 by suganyadevi.p

1 answer

Consider an infinitely long wire carrying a current I(t), with $ \frac {dI}{dt} = \lambda = constant$. Find the current produced in the rectangular loop of wire ABCD if its resistance is R, as shown in the fig.

asked Dec 30, 2016 by suganyadevi.p

1 answer

A magnetic field B is confined to a region $r \leq a$ and points out the paper (the Z axis) $ r = 0$ being the centre of the circular region. A charged ring (charge = Q) of radius b $b>a$ and mass m lies in the xy plane with its centre at the origin. the ring is free to rotate and is at rest. The magnetic field is brought to zero in time $\bigtriangleup t$. Find the angular velocity $\omega$ of the ring after the field vanister.

asked Dec 30, 2016 by suganyadevi.p

1 answer

If $\lambda$ is wave length of radio signals to be transmitted , then the length of Hertz antenna is

asked Sep 30, 2016 by meena.p

1 answer

The correct radiation between plasma frequency $\nu$ of a radio wave length and electron density N of the ionosphere

asked Sep 30, 2016 by meena.p

1 answer

What is the value of frequency at which an e.m wave must be propagated for the D- region to have a refractive index of $0.49 $ Electron density for D- layer is $10^9m^{-3}$

asked Sep 30, 2016 by meena.p

1 answer

A T.V transmission town antenna is at a height of 20 m . How much service area can it cover if the receiving antenna at a height of 25 m

asked Sep 30, 2016 by meena.p

1 answer

A T.V transmission town antenna is at a height of 20 m . How much service area can it cover if the receiving antenna at ground level

asked Sep 30, 2016 by meena.p

1 answer

Compute the LC product of a tuned amplifier circuit which requires a carrier wave of $1\;MHz$ for amplitude modulation

asked Sep 30, 2016 by meena.p

1 answer

The maximum amplitude of an A.M wave is found to be $3\;v$ What is modulation index?

asked Sep 30, 2016 by meena.p

1 answer

Two waves A and B frequencies $2\;MHz$ and $3MHz$ respectively are beamed in the same direction for communication via sky wave .Which one of there is likely to travel longer distance in the ionosphere before suffering total internal reflection ?

asked Sep 30, 2016 by meena.p

2 answers

Would sky waves be suitable for transmission of TV signal of $60\; MHZ$ frequency ?

asked Sep 30, 2016 by meena.p

1 answer

Which of the following :- Would produce digital signals

asked Sep 30, 2016 by meena.p

1 answer

Which of the following :- Would produce analog signals

asked Sep 30, 2016 by meena.p

1 answer

A TV transmission tower has a height of $240 \;m$ signal broad cast from this will be received by LOS Communication at a distance of (assume the radius of earth to be $6.4 \times 10^6 \;m)$

asked Sep 30, 2016 by meena.p

1 answer

An audio signal of $15\;KHz$ , frequency can not be transmitted over long distances without modulation because

asked Sep 30, 2016 by meena.p

1 answer

Identify the mathematical expression for amplitude modulated wave

asked Sep 30, 2016 by meena.p

1 answer

A basic communication system consists of A)transmitter B) Information Source C) User of information D) Channel E) receiver Choose the correct sequence in which these are arranged in a basic communication system

asked Sep 29, 2016 by meena.p

1 answer

A message signal of frequency $w_m$ is super posed on a carrier wave of frequency $w_c$ to get an amplitude modulated wave (Am). The frequency of the AM wave will be

asked Sep 29, 2016 by meena.p

1 answer

A speech signal of $3\;kHz$ is used to modulate a carrier signal of frequency $1\;MHz$ , using amplitude modulation . The frequencies of the side band will be

asked Sep 29, 2016 by meena.p

1 answer

A 1 Kw signal is transmitted using as communication channel which provides attention at the rate of $-2 dB$ per km. If the communication channel has a total length of 5 km , the power of the signal received is [ gain in $dB = 10 log \bigg( \Large\frac{P_0}{P_c}\bigg) ]$

asked Sep 29, 2016 by meena.p

1 answer

A $100\;m$ antenna is mounted on a $500\;m$ tall building . The complex can become transmission tower for waves with $\lambda$

asked Sep 29, 2016 by meena.p

1 answer

Three waves A,B and C of frequencies $1600\;kHz, 5 MHz$ and $60\;MHz$ respectively are to be transmitted from one place to another . Which of the following is the most appropriate mode of communication ?

asked Sep 29, 2016 by meena.p

1 answer

Two different coils have self inductance $L_1=8\;mH$ and $L_2=2\;mH$. At a certain instant , the current in the two coils is increasing at the same constant rate and the power supplied to the two coils is the same . Find the ratio of induced voltage at that instant

asked Sep 27, 2016 by meena.p

1 answer

1 Mw power is to be delivered from a power station to a town $10\;km$ away. One uses a pair of cer wires $0.5\;cm$ for this purpose . Calculate the fraction of ohmic losses to power transmitted if power is transmitted comment on the feasibility of doing this ?

asked Sep 27, 2016 by meena.p

1 answer

An electrical drive draws 2 kw power from AC mains [ Voltage $223 V(rms) = \sqrt {50,000}\;v$ ]. The current differs (lags) in phase by $\phi (\tan \phi = -\large\frac{-3}{4} )$ as compared to voltage . Find $I_{max}$ another device has twice the value of $R,X_c$ and $X_L$. How are the answers affected ?

asked Sep 27, 2016 by meena.p

1 answer

An electrical drive draws 2 kw power from AC mains [ Voltage $223 V(rms) = \sqrt {50,000}\;v$ ]. The current differs (lags) in phase by $\phi (\tan \phi = -\large\frac{-3}{4} )$ as compared to voltage . Find $ X_C - X_L$

asked Sep 26, 2016 by meena.p

1 answer

An electrical drive draws 2 kw power from AC mains [ Voltage $223 V(rms) = \sqrt {50,000}\;v$ ]. The current differs (lags) in phase by $\phi (\tan \phi = -\large\frac{-3}{4} )$ as compared to voltage . Find R

asked Sep 26, 2016 by meena.p

1 answer

Explain why the reactant offered by an inductor increased with increased frequency of an alternating voltage.

asked Sep 26, 2016 by meena.p

1 answer

Explain why the reactant provided by a capital to an alternating current decreases with increasing frequency .

asked Sep 26, 2016 by meena.p

1 answer

A $60\;w$ load is connected to the secondary of a transformer whose primary draws line voltage. If a current of $0.54\;A$ flows in the load, what is the current in the primary coil ? Comment on the type of transformer bring used ?

asked Sep 26, 2016 by meena.p

1 answer

A Coil of $0.01$ Henry inductance and 1 ohm resistance is connected to $200 \;volt,50 Hz,ac $ supply . Find the impedance of the circuit and time lag between max. alternating voltage and current .

asked Sep 26, 2016 by meena.p

1 answer

Both alternating current and direct current are measured in ampere. But how is the ampere defined defined for an alternating current .

asked Sep 26, 2016 by meena.p

1 answer

How does the sign of the phase angle $\phi$ , big which the supply voltage leads the current in an LCR series circuit , change as the supply frequency is gradually increased from very low to very high values ?

asked Sep 23, 2016 by meena.p

1 answer

Can the instantaneous power output of an ac source ever he negative ? can the average power output be negative ?

asked Sep 23, 2016 by meena.p

1 answer

In LC circuit , is considered analogous to a harmonically oscillating spring block system, which energy of LC circuit would be analogous to potential energy and which one analogous to kinetic energy ?

asked Sep 22, 2016 by meena.p

1 answer

The line that draws power supply to your house from street has

asked Sep 22, 2016 by meena.p

1 answer

For an LCR circuit , the power transferred forms the diving source to the drives oscillator is $P= I^2 z \cos \phi$

asked Sep 22, 2016 by meena.p

1 answer

Electrical energy is transmitted over large distance at high alternating voltage . Which of the following statement are correct ?

asked Sep 22, 2016 by meena.p

1 answer

In an alternating current circuit consisting of elements in series, the current increases on increasing the frequency of supply . Which of the following elements are likely to continue the circuit ?

asked Sep 22, 2016 by meena.p

1 answer

As the frequency of an ac circuit increase, the current first increase and then decrease . What combination of circuit elements is most likely to comprise the circuit ?

asked Sep 22, 2016 by meena.p

1 answer

The output of a step down transformer is measured to be $24\;v$ when connected to a 12 walt light bulb. The value of the peak current is

asked Sep 22, 2016 by meena.p

1 answer

An inductor of a reactance $1 \Omega$ and a resistor of $2 \Omega$ are connected in series to the terminals of a$6\;v(r.m.s)$ a.c source. The power dissipated in the circuit is

asked Sep 22, 2016 by meena.p

1 answer

Which of the following combination should be selected for better turning of an LCR circuit used for communication ?

asked Sep 21, 2016 by meena.p

1 answer

The voltmeter the resonant frequency in an L.C.R series circuit with a generator .

asked Sep 21, 2016 by meena.p

1 answer

When a voltage measuring device is connected to AC mains , the meter shows the steady input voltage opf $220\;v$ This means

asked Sep 21, 2016 by meena.p

1 answer

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