Question 1 :
For capacitors in the series combination, the total capacitance C is given by<br/><br/>
Question 2 :
The work done in bringing a unit positive charge from infinite distance to a point at distance x from a positive charge Q is W. Then the potential $\phi$ at that point is:
Question 3 :
The potential difference between the two plates of a parallel plate capacitor is constant. When air between the plates is replaced by dielectric material, the electric field intensity :<br/>
Question 4 :
Choose the correct answer from the alternatives given.<br/>In order establish an instantaneous displacement current of 1 mA in the space between the plates of 2 $\mu F$ parallel plate capacitor. the rate of change of potential difference is:
Question 5 :
A capacitor of capacity $10\ \mu F$ is charged to a potential of $10000\ V$ and a wire is stretched by $0.2\ m$ by a force of $5000\ N$. The ration of the potential energies stored in them will be
Question 6 :
The capacity of a parallel plate condenser without any dielectric is C. If the distance between the plates is doubled and the space between the plates is filled with a substance of dielectric constant $3$, the capacity of the condenser becomes:
Question 7 :
What is the ratio of electric field intensity at distance $5$ cm to that at $10$ cm from a point charge $Q$ in air?<br/>
Question 8 :
Eight dipoles of charges of magnitude $e$ are placed inside a cube. The total electric flux coming out of the cube will be
Question 10 :
If $10^{10}$ electrons are acquired by a body every second, the time required for the body to get a total charge of $1\  C$ will be :
Question 11 :
Two infinitely long parallel conducting plates having surface charge densities$\displaystyle +\sigma$ and$\displaystyle -\sigma$respectively, are separated by a small distance. The medium between the plates is vacuum. If$\displaystyle { \varepsilon }_{ 0 }$is the dielectric permittivity of vacuum then the electric field in the region between the plates is:
Question 12 :
Let $E_1(r), E_2(r)$ and $E_3(r)$ be the respective electric fields at a distance r from a point charge Q, an infinitely long wire with constant linear charge density $\lambda$, and an infinite plane with uniform surface charge density $ \sigma $. lf $E_1(r_0) = E_2(r_0) = E_3(r_0)$ at a given distance $r_0$, then :<br/>
Question 13 :
In cyclotron, for a given magnet, radius of the semicircle traced by positive ion is directly proportional to__________. (v=velocity of positron ion)<br/>
Question 14 :
In cyclotron, for a given magnet, radius of the semicircle traced by positive ion is directly proportional to ($v=$ velocity of positive ion).<br/>
Question 15 :
A current carrying loop lies on a smooth horizontal place. Then<br>
Question 16 :
Electron of mass m and charge q is travelling with a speed v along a circular path of radius r at right angles to a uniform magnetic field of intensity B. If the speed of the electron is doubled and the magnetic field is halved the resulting path would have a radius.<br>
Question 17 :
An electron of charge e and mass m is moving in circular path of radius r with a uniform angular speed . Then which of the following statements are correct?
Question 18 :
A doubly ionized $He^{+2}$ atom travels at right angles to a magnetic field of induction $0.4 T$ at a velocity of $10^{5}m/s$ describing a circle of radius $r$. A proton traveling with same speed in the same direction in the same field will describe a circle of radius : <br/>
Question 19 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"><p class="wysiwyg-text-align-left">The magnetic force required to demagnetise the material is</p>
Question 21 : <p>The relation between magnetic permeability, $\mu$ and field strength, $H$ for a specimen of iron is as follows $\mu =\left [ \dfrac{0.4}{H}+12\times 10^{-4} \right ]$ Henry / meter. The value of $H$ which produces flux density of $1T$ will be :<br/></p>
Question 24 :
If relative permeability of iron is 2000. Its absolute permeability in S.I. units is
Question 25 :
The horizontal component of the earth's magnetic field at a place is $3 \times 10 ^ { - 4 } T$and the dip is $\theta$ = $t a n ^ { - 1 }$ (4/3). A metal rod of length 0. 25 m placed in the north-south position is moved at a constant speed of 10 cm/s towards the east. The e.m.f induced in the rod will be:
Question 26 :
When a rectangular coil is rotated in a uniform magnetic field about an axis passing through its centre and perpendicular to the field, the emf induced in the coil varies:
Question 27 :
If area of a long solenoid is doubled,length is trippled and no. of turns are remained contant.Then its self-inductance will be changed how many times-<br>
Question 28 :
The number of turns in the coil of an AC generator ar e$100$ and its cross-sectional area is $2.5{m}^{2}$. The coil is revolving in a uniform magnetic field of strength $0.3T$ with the uniform angular velocity of $60rad/s$. The value of maximum value produced is _____kV
Question 29 :
A coil is placed in transversemagnet field of $0.02T$. If this coil starts shrinking at a rate of $1mm/sec$, while its radius remains $4cm$, then what is the value of induced $emf$?
Question 30 :
Two identical coaxial circular loops carry a current I each<br/>circulating in the same direction If the loops approach each other, you will observe that<br/>
Question 31 :
An ideal transformer has 400 turns in the primary and 200 turns in the secondary. If the primary is connected to a 12 V battery, then the secondary voltage is<br/>
Question 33 :
An inductor $20\ mH$, a capacitor $50\ \mu F$ and a resistor $40\ \Omega$ are connected in series across a source of emf $V=10\sin 340t$. The power loss in A.C. circuit is:
Question 34 :
A current $i_0$ is flowing through an $L-R$circuit of time constant $t_0$. The source of the current is switched off at time $t = 0$. Let $r$be the value of $(-di/dt)$at time $t=0$. Assuming this rate to be constant, the current will reduce to zero in a time interval of:
Question 35 :
A $0.21\space H$ inductor and a $12\Omega$ resistance are connected in series to a $220\space V, 50\space Hz$ ac source. The phase angle between the current and the source voltage is :
Question 36 :
A step-down transformer with an efficiency of $80\%$ is used on a 1000 V line to deliver10 A at 100 V at the secondary coil. The Current drawn from the line is
Question 37 :
A battery of $9V$ is connected in series with resistors of $0.5, 0.3, 0.4, 0.2$, and $12$. How much current would now through the $0.4$ resistors?
Question 38 :
An energy source will supply constant current into the load if its internal resistance is :
Question 39 :
A potentiometer wire of length $200$cm has a resistance of $20\Omega$. It is connected in series with a resistance of $10\Omega$ and an accumulator of emf $6$V having negligible internal resistance. A source of $2.4$V is balanced against a length L of the potentiometer wire. The value of L is?
Question 40 :
A strip of copper and another germanium are cooled from room temperature to 80 K. Theresistance of
Question 41 :
A material $B$ has twice the specific resistance of $A$. A circular wire made of $B$ has twice the diameter of a wire made of $A$. Then for the two wires to have the same resistance, the ratio $l_{B} $ / $l_{A}$ of their respective lengths must be:
Question 42 :
The equivalent resistance of eight equal resistances in series is $48$ ohms. What would be the equivalent resistance if they are connected in parallel?
