Download App

Current Electricity — Physics STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 SciencePhysicsCurrent Electricity2 Marks
Question
Two metallic wires A and B made from same substance have equal lengths and their cross-sections are in the ratio $1: 2$. They are joined in (i) series (ii) parallel. In both the above combinations, compare the drift velocities of electrons in the two wires.
✓

Answer

$A _1: A _2=1: 2=l_2=1$
(i) On joining in series, the electric current is same.
$I _{ A }= I _{ B } \Rightarrow n e A_1\left(v_d\right)_1=n e A_2\left(v_d\right)_2$
or $\frac{\left(v_d\right)_1}{\left(v_d\right)_2}=\frac{ A _2}{A_1}=\frac{2}{1}=2: 1$
(ii) In parallel combination, potential difference remains the same
Hence, $V_A=V_B \Rightarrow I_A \times R_A=I_B \times R_B$
$\Rightarrow n e A_1\left(v_d\right)_1 \times \rho \frac{1}{A_1}=n e A_2\left(v_d\right)_2 \times \rho \frac{1}{A_2}$
$\Rightarrow \quad \frac{\left(v_d\right)_1}{\left(v_d\right)_2}=1 \Rightarrow\left(v_d\right)_1:\left(v_d\right)_2=1 ; 1$ Ans.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "Short Answer Type Questions [2M]" from Current Electricity→Current Electricity — all question types→Physics STD 12 Science question papers→Bihar Board STD 12 Science question papers→Bihar Board question paper generator→

Similar questions

In a cylindrical conductor, a direct current is flowing. Is there any electric field inside the conductor?
→
The current generator Ig shown in figure, sends a constant current i through the circuit. The wire ab has a length l and mass m and can slide on the smooth, horizontal rails connected to Ig. The entire system lies in a vertical magnetic field B. Find the velocity of the wire as a function of time.

→
A semicircular wire of radius 5.0cm carries a current of 5.0A. A magnetic field B of magnitude 0.50T exists along the perpendicular to the plane of the wire. Find the magnitude of the magnetic force acting on the wire.
→
Which of the following can act as a source of electromagnetic waves:
  1. A charge moving with a constant velocity.
  2. A charge moving in a circular orbit.
  3. A charge at rest.
Give reason.
→
The electric force experienced by a charge of 1.0 × 10-6C is 1.5 × 10-3N. Find the magnitude of the electric field at the position of the charge.
→
Two identical loops, one of copper and the other of aluminium, are rotated with the same angular speed in the same magnetic field. Compare (i) the induced emf and (ii) the current produced in the two coils. Justify your answer.
→
As temperature increases, the viscosity of liquids decreases considerably. Will this decrease the resistance of an electrolyte as the temperature increases?
→
The maximum torque acting on a coil of effective area $0.04 m^2$ is $4 \times 10^{-8} Nm$ when the current in it is 100 pA . Find the magnetic induction in which it is kept.
→
Using Bohr model, calculate the electric current created by the electron when the H-atom is in the ground state.
→
Explain, with the help of a circuit diagram, the working of a p-n junction diode as a half-wave rectifier.
→