42 - Magnetism Questions Answers
two short magnets of equal dipole momet M are fastened perpedicularat their centre.the magnitude of magnetic feild at adistance d from the centre on the bisector of right angles is?
the resultant dipole moment is √2M thus the resultant magnetic field is μ2√2M/4πd3 (ans)
this answer is given by sarika and is correct answer
is impedence as same as resistanace in a circuit // and // are capacitive reactance and inductive reactance constant values(i.e. independant of value of current in ac circuit at any time) ??
Write the question with correct symbols
yes it is equivalent to resistance for that circuit
A SIMPLE ELECTRIC MOTOR HAS AN ARMATURE RESISTANCE OF 1 ohm & RUNS FROM A D.C SOURCE OF 12V . IT DRAWS A CURRENT OF 2A WHEN UNLOADED . WHEN A CERTAIN LOAD IS CONNECTED TO IT ,IT SPEED REDUCES BY 10% OF ITS INITIAL VALUE ,THE CURRENT DRAWN BY THE UNLOADED MOTOR IS??
ANS 3A
R=1ohm , E=12V , I=2A
I=(E-e)/R => e=10 ON PUTTING D VALUES
NOW AS IT IS REDUCES BY 10% MEANS NOW e' = 9V ( 10/100 X 10 = 1 CHANGE , THUS FINAL = 10-1=9)
I= E-e'/R = ( 12-9)/ 1 = 3A (RESISTANCE IS KEPT CONST.) RESISTANCE WILL CHANGE OR NOT??
yes this method is correct.
velocity of e- in hydrogen atom is 2X106 m/s . the radius of orbit is 5X10-11 m . the mag induction at centre of orbit in T will be??
B = μ0/2 * i/r
and i = e/T
and T = 2πr/v
solve
potential diff b/w dees of cyclotron is V , if charge q comes out of it after completing n revolution then gain in KE of charge is 2nqV HOW?
when charge will move from first dee to second dee it will gain qV and on returning to first dee it will gain qV again so in one revolution it will gain 2qV so in n revolutions it will gain 2qVn
velocity of e- in hydrogen atom is 2X106 m/s . the radius of orbit is 5X10-11 m . the mag induction at centre of orbit in T will be??
B = μ0/2 * i/r
i = e/T
and T = 2πr/v
now solve
chock coil is used to
1) increase current
2) increase voltage
3) decrease current
4) decrease voltage
here we know power= IV & chock coil is used to reduce the power loss , so here what vyl be the answer
chock coil in ac is the device equivalent to rheostat in dc, so it is used to increase current.
A CHARGED PARTICLE IS PROJECTED PARALLEL TO A UNIFORM FIELD . THE PATH OF D PARTICLE WILL BE
1) PARABOLIC
2) ELLIPTICAL
3) CIRCULAR
4) LINEAR
linear and accelerated.
Q 1-when current passes through a solenoid .then what happens to the length of solenoid?
Q2-a current carrying wire carrying current i normally into the paper at the centreof current carring circular ring.the magnetic force acting on the circular ring is ?
Q3- To increase the current through the solenoid from 1A TO 2A ,30J work is done by thr battery.work done by the same battery in increasing the current from 3A TO 4A IS?
Q4- When a closed looop is held stationary in magnetic field b/w north & south pole of 2 permanent magnets of different dipole moments , then current will be induced in the loop or not?
1. the length will decrease as the current in the two consecutive turns of the solenoid are in same direction. which will create an atrraction.
2. since B produced by the wire is parllel to the direction of dl so net force will be 0
3.dw = Lidi first take limit 1 to2 and w=30 to find the L (INTEGERATE)
After than again use the above formula taking limit 3 to 4 .put L here ,L= 20
the answer is 70J.
4. I think no emf will be induced as the flux is not changing.
These answers by NIKHIL VARSHNEY are correct
in the previous case if north pole is brought near the mettalic ring why the direction is reversed. we have to consider the drn of magnetic field of magnet or not. if yes then which drn N-S or S-N.