Question 1 : When a sheet of metal is placed in a magnetic field, which changes from zero to a maximum value, the induced currents are set up in the direction shown in figure. What is the direction of magnetic field.<br> <img style='object-fit:contain' width='130' height='133' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea28a218ab67a08eba54f0b">
Question 2 :
Whenever a magnet is moved either towards or away from a conducting coil, an emf is induced, the magnitude of which is independent of
Question 3 :
The number of turns in primary and secondary coils of a transformer is 50 and 200 respectively. If the current in the secondary coil is 4A, then the current in the secondary coil is
Question 4 :
In a current carrying long solenoid, the field produced does not depend upon
Question 6 :
If 25 A current is drawn by 220 V motor and back emf produced is 80 V, the value of armature resistance is
Question 7 :
In an ideal choke, ratio of its inductance <i>L </i>to its DC resistance <i>R</i> is
Question 8 :
When the current changes from +2 A to -2 A in 0.05 s, an emf of 8 V is induced in a coil. The coefficient of self-induction of the coil is
Question 10 : The current from <img style='object-fit:contain' width='39' height='20' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea289143c680714de9a838c"> is increasing in magnitude. What is the direction of induced current, if any, in the loop shown in figure.<br> <img style='object-fit:contain' width='126' height='66' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea289143c680714de9a838d">
Question 11 :
Turn ratio is 1.25. The step up transformer operates at 230 V and current through secondary is 2 A. Then current in primary is
Question 12 :
A transformer rated at 10k W is used to connect a 5 kV transmission line to a 240 V circuit. The ratio of turns in the windings of the transformer is
Question 13 :
The primary winding of a transformer has 100 turns and its secondary winding has 200 turns. The primary is connected to an A.C. supply of {tex} \mathrm {120 V } {/tex} and the current flowing in it is {tex} \mathrm {10A } {/tex}. The voltage and the current in the secondary are
Question 14 : A metallic square loop ABCD is moving in its own plane with velocity v in a uniform magnetic field perpendicular to its plane as shown in figure. An electric field is induced <br> <img style='object-fit:contain' src="https://data-screenshots.sgp1.digitaloceanspaces.com/5d61014570b43a6d486d17c8.jpg" />
Question 15 : The figure shows certain wire segments joined together to form a coplanar loop. The loop is placed in a perpendicular magnetic field in the direction going into the plane of the figure. The magnitude of the field increases with time. {tex}I_{1}{/tex} and {tex}I_{2}{/tex} are the currents in the segments ab and cd. Then, <br>
<img style='object-fit:contain' src='https://storage.googleapis.com/teachmint/question_assets/NEET/5eb2813ccd357a12648729b9' class="uploaded-image" /> <br>
Question 16 :
Two solenoids of equal number of turns have their lengths and the radii in the same ratio {tex} 1 : 2 . {/tex} The ratio of their self inductances will be
Question 17 : In a coil of resistance 100Ω a current is induced by changing the magnetic flux through it as shown in the figure The magnitude of change in flux through the coil is<br><center> <img style='object-fit:contain' src='https://storage.googleapis.com/teachmint/question_assets/NEET/5ece4d87eab619455fcb78b4' class="uploaded-image" height="120" /></center>
Question 18 :
When the current changes from {tex} + 2 \mathrm { A } {/tex} to {tex} - 2 \mathrm { A } {/tex} in 0.05 second, an e.m.f. of 8{tex} \mathrm { V } {/tex} is induced in a coil. The coefficient of self- induction of the coil is
Question 19 :
A magnetic field of {tex}2\times 10^{-2}{/tex} T acts at right angles to a coil of area {tex}100 cm^{2}{/tex}, with 50 turns. The average e.m.f induced in the coil is 0.1 V when it is removed from the field in t sec. The value of t is
Question 20 :
A conducting ring of radius 1{tex} \mathrm { m } {/tex} kept in a uniform magnetic field {tex} B {/tex} of {tex} 0.01 T , {/tex} rotates uniformly with an angular velocity 100{tex} \mathrm { rad } \mathrm { s } ^ { - 1 } {/tex} with its axis of rotation perpendicular to {tex} B {/tex} . The maximum induced emf in it is
Question 21 :
A metal ring is held horizontally and bar magnet is dropped through the ring with its length along the axis of the ring. The acceleration of the falling magnet
Question 22 :
When current in a coil changes from {tex} \mathrm { 5A } {/tex} to {tex} \mathrm { 2A } {/tex} in {tex} \mathrm { 0.1s } {/tex} , average voltage of {tex} \mathrm {50 V } {/tex} is produced. The self-inductance of the coil is :
Question 24 :
Name the high energetic invisible electromagnetic wave which helps in the study of structure of crystals.<br>
Question 26 :
Choose the correct answer from the alternatives given.<br>Which of the following electromagnetic waves have the smallest wavelength?
Question 29 :
When cathode rays strike a metal target of high melting point with very high velocity, then
Question 31 :
The frequencies of X-rays, $\gamma-rays$ and ultra violet rays are respectively $p, q$ and $r$, then
Question 32 :
A certain color of light towards the purple end of the visible spectrum has a wave length of $420\, nm$ in vacuum.<br/>What is the frequency of this light? (The speed of light in a vacuum is $3.00 \times 10^8 \, m/s$).
Question 34 :
The wavelength of the short radiowaves, micro waves, ultraviolet waves are ${ \lambda }_{ 1 }, { \lambda }_{ 2 }$ and ${ \lambda }_{ 3 }$ respectively. Arrange them in decreasing order.
Question 35 :
The operating voltage in coolidge tube is ${10}^{5}V$. The speed of X-Rays produced is ________ $m{s}^{-1}$
Question 37 :
The wave length of light in visible part $ \left(\lambda_{V}\right) $ and for sound $ \left(\lambda_{S}\right) $ are related as
Question 39 :
If $v_{g}, v_{x}$, and $v_{m}$ are speeds of gamma rays, $X$ rays, and microwaves respectively in vacuum, then:
Question 40 : Match the List -I (Phenomenon associated with electromagnetic radiation) with List - II (Part of electromagnetic spectrum) and select the correct code from the choices given below the <br><table class="wysiwyg-table"><tbody><tr><td><br></td><td>List - I<br></td><td><br></td><td>List - II<br></td></tr><tr><td>I<br></td><td>Doublet of sodium<br></td><td>A<br></td><td>Visible radiation<br></td></tr><tr><td>II<br></td><td>Wavelength corresponding to temperature associated with the isotropic radiation filling all space<br></td><td>B<br></td><td>Microwave<br></td></tr><tr><td>III<br></td><td>Wavelength emitted by atomic hydrogen in interstellar space<br></td><td>C<br></td><td>Short radiowave<br></td></tr><tr><td>IV<br></td><td>Wavelength of radiation arising from two close energy levels in hydrogen<br></td><td>D<br></td><td>X-rays<br></td></tr></tbody></table>
Question 41 :
A small metallic ball is suspended in a uniform electric field by a thread. If high energy X-rays are made to fall on it , then:
Question 42 :
Which of the following electromagnetic waves is used in medicine to destroy cancer cell?
Question 45 :
A metal plate gets heated when cathode rays strike against it due to
Question 46 :
Which of the following is not the property of a cathode ray
Question 48 :
Which of the following metal thermionically emits an electron at a relatively lowest temperature among them
Question 49 : Sodium and copper have work functions <img style='object-fit:contain' width='39' height='20' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea28cee8ab67a08eba551b6"> and <img style='object-fit:contain' width='39' height='20' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea28de53c680714de9a8b90"> respectively. Then the ratio of their threshold wavelengths is nearest to
Question 50 :
Photoelectric work function of a metal is 1eV. Light of wavelength {tex}\lambda = 3000 {\text{Å}}{/tex} falls on it. The photo electrons come out with velocity
Question 53 : If an electron oscillates at a frequency of <img style='object-fit:contain' width='39' height='20' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea28e6c8ab67a08eba55624"> it gives
Question 54 :
In a discharge tube ionization of enclosed gas is produced due to collisions between
Question 55 :
The number of photo-electrons emitted per second from a metal surface increases when
Question 58 :
In photoelectric effect, stopping potential for a light of frequency {tex} \mathrm { n } _ { 1 } {/tex} is {tex} \mathrm { V } _ { 1 } {/tex} . If light is replaced by another having a frequency {tex} \mathrm { n } _ { 2 } {/tex} then its stopping potential will be
Question 59 :
According to photon theory of light which of the following physical quantities associated with a photon do not/does not change as it collides with an electron in vacuum
Question 60 :
Monochromatic light of frequency {tex} 6.0 \times 10 ^ { 14 } \mathrm { Hz } {/tex} is produced by a laser. The power emitted is {tex} 2 \times 10 ^ { - 3 } \mathrm { w } {/tex} . The number of photons emitted, on the average, by the sources per second is
Question 61 :
An electron of mass {tex} \mathrm { m } {/tex} and a photon have same energy E. The ratio of de-Broglie wavelengths associated with them is:
Question 62 : During <img style='object-fit:contain' width='10' height='20' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea28cbe8ab67a08eba5518a"> -ray production from coolidge tube if the current in increased, then
Question 63 : The photoelectric threshold wavelength for a metal surface is 6600 <img style='object-fit:contain' width='9' height='21' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea28cea8ab67a08eba5519d"> . The work function for this metal is
Question 64 : Light of wavelength 4000 <img style='object-fit:contain' width='9' height='21' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea28cea8ab67a08eba5519d"> is incident on a metal plate whose work function is 2 eV. The maximum KE of the emitted photoelectron would be
Question 65 : From the figure describing photoelectric effect we may infer correctly that <br> <img style='object-fit:contain' width='251' height='176' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea28eeaaaa71c51ed68b4b4">
Question 66 :
A strong argument for the particle nature of cathode rays is that they
Question 68 :
The threshold frequency for a metallic surface corresponds to an energy of 6.2{tex} \mathrm { eV } {/tex} and the stopping potential for a radiation incident on this surface is 5{tex} \mathrm { V } {/tex} . The incident radiation lies in
Question 69 :
In photoelectric effect the work function of a metal is 3.5{tex} \mathrm { eV } {/tex} . The emitted electrons can be stopped by applying a potential of {tex} - 1.2 \mathrm { V } . {/tex} Then
Question 70 : In an <img style='object-fit:contain' width='10' height='20' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea28cbe8ab67a08eba5518a"> -rays tube, the intensity of the emitted <img style='object-fit:contain' width='10' height='20' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea28cbe8ab67a08eba5518a"> -rays beam is increased by
Question 72 :
Which metal will be suitable for a photoelectric cell using light of wavelength <b>4000 Å</b>. The work functions of sodium and copper are respectively <b>2.0 eV</b> and <b>4.0 eV</b>
Question 73 :
G. P. Thomson experimentally confirmed the existence of matter waves by the phenomenon
Question 74 :
A and B are two metals with threshold frequencies {tex} 1.8 \times 10 ^ { 14 } \mathrm { Hz } {/tex} and {tex} 2.2 \times 10 ^ { 14 } \mathrm { Hz } {/tex} . Two identical photons of energy 0.825 eV each are incident on them. Then photoelectrons are emitted in ( Take h = {tex} 6.6 \times 10 ^ {- 34 } {/tex} Js)
Question 75 :
An X-ray tube is operated at 15{tex} \mathrm { kV } {/tex} . Calculate the upper limit of the speed of the electrons striking the target.
Question 76 :
A proton has kinetic energy {tex} \mathrm { E } = 100 \mathrm { keV } {/tex} which is equal to that of a photon. The wavelength of photon is {tex} \lambda _ { 2 } {/tex} and that of proton is {tex} \lambda _ { 1 } . {/tex} The ratio of {tex} \lambda _ { 2 } / \lambda _ { 1 } {/tex} is proportional to
Question 77 :
When photons of energy hv fall on an aluminium plate (of {tex} \left. \text { work function } \mathrm { E } _ { 0 } \right) , {/tex} photoclectrons of maximum kinetic energy {tex} \mathrm { K } {/tex} are ejected. If the frequency of the radiation is doubled, the maximum kinetic energy of the ejected photoelectrons will be
Question 78 :
Photons of energy of 6 eV are incident on a metal surface whose work function is 4 eV. The minimum kinetic energy of the emitted photoelectrons will be
Question 81 :
A particle of mass 1{tex} \mathrm { mg } {/tex} has the same wavelength as an electron moving with a velocity of {tex} 3 \times 10 ^ { 6 } \mathrm { ms } ^ { - 1 } {/tex} . The velocity of the particle is:
