Question 1 :
A step-down transformer reduces the voltage of a transmission line from $2200\ V$ to $220\ V$. The power delivered by it is $880\ W$ and its efficiency is $88$%. The input current is :

Question 4 :
In a primary coil $5 A$current is flowing on$220$volts. If thesecondary coil produces$2200V$voltage. Then the ratioof number of turns insecondary coil and primary coil will be

Question 5 :
In a transformer, number of turns in primary and secondary are 500 and 2000 respectively. If current in primary is 48 A, current in the secondary is :

Question 6 :
The capacitance in an oscillatory LC circuit is increased by 1%. The change in inductance required to restore its frequency of oscillation is to

Question 7 :
When $ 100 $ volt dc is applied across a coil, a current of $1$ amp flows through it. When $ 100$ volt ac at $ 50$ cycle $s^{-1} $ is applied to the samecoil, only $0.5$ ampere current flows. The impedance of the coil is

Question 8 :
A resistor R, an inductor L and a capacitor C are connected in series to a source of frequency $n$. If the resonant frequency is $n$, then the current lags behind voltage, when

Question 9 :
An alternating e.m.f. of $E= 100 \sin(100 \pi$t ) is&#160;connected to a choke of negligible resistance and&#160;current oscillations of amplitude 1 A are&#160;produced. The inductance of the choke should&#160;be<br/>

Question 10 :
Two different coils have self inductance $L_{1}=8$ <br> $mH$ and $L_{2}=2$ <br> $mH$. The currents in both are increasing at the same constant rate. At a certain instant of time, the power given to the two coils is the same. At this moment the current, the induced voltage and energy stored in the first coil are $i_{1}$ , $V_{1}$ and $U_{1}$ respectively. The corresponding values in the second coil are $i_{2}$, $V_{2}$ and $U_{2}$&#160; respectively. Then the values of $\dfrac{i_{1}}{i_{2}},\dfrac{V_{1}}{V_{2}}$ and $\dfrac{U_{1}}{U_{2}}$ are respectively :<br/>

Question 11 :
In an interference experiment, intensity ratio at the bright to dark fringe is $9 : 1$. Amplitudes of interfering waves was in the ratio.

Question 12 :
White light is used to illuminate two slits in&#160;Young's double slit experiment. Separation&#160;between the slits is b and the screen is at a&#160;distance d (&gt;&gt; b) from the slits. Then wavelengths&#160;missing at a point on the screen directly in front of one of the slits are&#160;<br/>

Question 13 :
Light of wavelength $500nm$ goes through a pinhole of $0.2mm$ and falls on a wall at a distance of $2m$. What is the radius of the central bright spot formed on the wall?

Question 14 :
An unpolarized beam of light is incident on a group of four polarizing sheets, which are arranged in such a way that the characteristic direction of each polarizing sheet makes an angle of $30^{\circ}$ with that of the preceding sheet. The fraction of incident unpolarized light transmitted is

Question 15 :
A charge of 4Q is transferred to a solid metal sphere of radius r. Where will this excess charge reside?

Question 16 :
An air capacitor C connected to a battery of e.m.f. V acquires a charge q and energy E. The capacitor is disconnected from the battery and a dielectric slab is placed between the plates. Which of the following statements is correct?<br>

Question 17 :
Three capacitors $3\mu F,9 F$ and $18\mu F$ are connected first in series and then in parallel. The ratio of the equivalent capacitance in two cases is :

Question 18 :
A parallel plate capacitor has a uniform electric field $E$ in the space between the plates. If the distance between the plates is $d$ and area of each plate is $A$, the energy stored in the capacitor is :

Question 19 :
Two condensers of capacity $0.3 \mu F$ and $0.6 \mu F$ respectively are connected in series. The combination is connected across a potential of $6$ volts. The ratio of energies stored by the condensers will be:

Question 20 :
A parallel plate capacitor without any dielectric within its plates, has a capacitance C, and is connected to a battery of emf V. The battery is disconnected and the plates of the capacitor are pulled apart until the separation between the plates is doubled. What is the work done by the agent pulling the plates apart, in this process?

Question 22 :
Threeequal resistors connected in series acrossa source of e.m.f. together dissipate 10 watt ofpower. What would be the power dissipated if thesame resistors are connected in parallel across the same source of e.m.f.?<br>

Question 24 :
The temperature dependence of resistances of Cu and undoped Si in the temperature range $300-400$K, is best described by.

Question 25 :
An alternating voltage $V=30\ \sin {50t}+40\ \cos {50t}$ is applied to a resistor of resistance $10\ \Omega$. The rms value of current through resistor is:

Question 27 :
Assertion: STATEMENT-1 : The current density $\vec{J}$ at any point in ohmic resistor is in direction of electric field $\vec{E}$ at that point. Reason: STATEMENT-2 : A point charge when released from rest in a region having only electrostatic field always moves along electric lines of force.

Question 28 :
The particles which can be added to the nucleus of an atom, without changing properties, are called.

Question 29 :
The electric flux $\phi$ through a hemispherical surface of radius R, placed in a uniform electric field of intensity E parallel to the axis of its circular plane is :

Question 31 :
A charge Q is distributed uniformly in a sphere (solid). Then the electric field at any point r where r &lt; R (R is radius of the sphere) varies as

Question 32 :
Charges Q, 2Q and 4Q are uniformly distributed in three dielectric solid spheres 1,2 and 3 of radii R/2,R and 2R respectively. If magnitudes of the electric fields at point P at a distance R from the centre of sphere 1, 2 and 3 are $E_1$, $E_2$ and $E_3$ respectively, then :<br/>