99 Percentile Qs Bank for JEE MainPhysicsCurrent Electricity
Charge passing through a conductor of cross-section 0.3 ~m ^2 is given by q = (3 t ^2+5 t +2 ) C where ' t ' is in seconds. The drift velocity at t=2 ~s is (Concentration of electrons in the conductor =2 10²⁵ ~m ⁻³ )
Options
- A0.77 10⁻⁵ ~ms ⁻¹
- B0.93 10⁻⁵ ~ms ⁻¹
- C1.77 10⁻⁵ ~ms ⁻¹
- D2.08 10⁻⁵ ~ms ⁻¹
Correct answer
C. 1.77 10⁻⁵ ~ms ⁻¹
Step-by-step solution
Given, area of cross-section A =0.3 ~m ^2 , aligned & n =2 10²⁵ ~m ⁻³ charge, q = (3 t ^2+5 t +2 ) C , & t =2 ~s , ~V _ d =? & ~V _ d = i neA = dq / dt neA [ i = dq dt ] & i = dq dt = d dt (3 t ^2+5 t +2 )=6 t +5=6 2+5 & =17 & V _ d = i neA = 17 2 10²⁵ 1.6 10⁻¹⁹ 0.3 & = 17 0.96 10^6 =1.77 10⁻⁵ ~m / s aligned