Question

1) Two resistors are connected to each other in parallel, one resistor has a known value of R, the R resistance of the second one is unknown. If the equivalent of two resistors in parallel is equal to 2 what is the resistance of the second one? A) R B) 2R C) D) E) 4R EN 2) Which one of the following sentences is correct about the velocity selector? A) The velocity of charged particles leaving a velocity selector are the same for all particles independent value of charge and value of mass. B) Velocity of a charged particle leaving a velocity selector is equal to v = B/E C) The velocity of a charge leaving the selector is independent of electric field. D) A velocity selector is made up of magnetic field and electric field which are parallel with respect to each other. E) The velocity of charge leaving the selector is independent of the magnetic field. 3) A charged particle is moving with velocity of Vin a magnetic field of B, which one of the followings is correct: A) The direction of force F on the charge is parallel to magnetic field B B) The direction of force F on the charge is parallel to velocity direction V C) The force is maximized when velocity direction and magnetic field are parallel D) The force F is perpendicular (normal) to both velocity Vand magnetic field B E) The direction of force on positive charge or negative charge would be the same

Answer 1

are second Two resistors conneited in to each other in paralld, one resistor has known value R and other resistance of one is unknown paralel onbination given betont these two resistênces The co are R B A R' is 을 Where R" is resistance of unknown resistor, we have to find out value of Ri The equivalent resistance of parallel combination of R and R' Ria & toko & +1 / SO, 2 R RI ar pra § rol - R' ون R=R so, option ② is correct. device which 2. velocity selectoris consists tão is made perpendicular magnetic field and electue se of consists peopend field an a shown in figure. + HE VFElB 1-E/B 03 VEE

ket a pa charged particle, a moves to the through above region, the particles were the Now electrue force this charge FEE magnetic force on this charge E o qlox =qvB sin goo and - IUB It is velocity of particle] Now, if o magnitude of. fe and Em and opp tie then re same Fe - Fm 091 qE z qUB 091, V2 E B The charged particle moves with above velocity lie. v. t will will win fall flow to its initial path but for the particles moves with other velocity the, uz Es will be deflected from it initial path as sho in figure. Hence option is correct. wn

3, on The force charged particle in a magnetic field B moving with velocity is FETXB) The result of u x B the vector E The direction of heat force ? is perpendicular to both w and hand and somand and e and B are in the same plane Dis correct. Hence option 1 are wrong so. option A and B when o and B wie paralled then ) 8 x B=0 so, & = o irre, force is minimum so, option © is wrong. the direction of force on the positive charge and negative charge will be opposite due to sign of charge.so, option @ is wrong. Hence option o Is correct.