Electric Circuits Answers

A wire with resistance of 80Ω is drawn out through a die so that its new length is three times its original length. Find the resistance of the longer wire assuming that the resistivity and density of the material are unaffected by the drawing process.

a. 72Ω

b. 60Ω

c. 80Ω

d. 45Ω

Calculate the resistance of 180 m of silver wire having a cross section of 033mm^2. The resistivity of silver is 16×10−8Ωm

a. 112Ω

b. 96Ω

c. 146Ω

d. 75Ω

A tiny ball of mass 0.60 g is suspended from a rigid support with a piece of thread in a horizontal electric field of intensity 700 N/C. The ball is in equilibrium when the thread is inclined at an angle of
20 degrees to the vertical. What are the magnitude and sign of the charge on the ball? Take g=9.8m/s^2

a. −3.1×10^−6C

b. 3.2×10^−6C

c. 4.2×10^−6C

d. −4.1×10^−3C

What are the dimensions of the constant k in Coulomb’s law of electrostatics?

a. ML^2T^−4T^−2A^−1

ML^2T^3A^−2

M^−2L^3T^2A^−1

ML^3T^−4A^−2

The total electric flux through a cylinder placed in an electric field with its axis parallel to the field is zero.
8 Charges of +2C and −2C are situated at points P and Q respectively which are at a distance apart. A point X is mid-way between P and Q. Which of the following correctly describes the electric field and the electric potential at point X

a. electric field is toward Q, electric potential is zero.

b. electric field is toward Q, electric potential is negative.

c. electric field is toward P, electric potential zero.

d. electric field is toward P, electric potential is positive.

Which of the following is not true about the electric field intensity E⃗ of a uniformly charged solid sphere?

a. E⃗ is maximum at the surface of the sphere

b. E⃗ is directly proportional to the distance from the centre of the sphere

c. E⃗ decreases as a square of the distance from the surface of the sphere

d. E⃗ decreases as a square of the distance from the centre of the sphere.

1 volt is equal to

a. 1 watt/C

b. 1 J/s C

c. 1 J/C

d. 1 N/C

The electric potential difference between two points A and B is 42 V. What is the work done by an external agent in carrying a charge of 5.0×10−5C from A to B at constant speed?

a. 2.1×10^−3J

b. 8.4×10^−4J

c. 21×10^−4J

d. 8.4×10^−3J

The electron beam in a television tube consists of electrons accelerated from rest through a potential difference of about 20,000V. What is the speed of the electrons? (Ignore relativistic effects). Electron rest mass is 9.11×10^−31 kg and electronic charge is 1.6×10^−19 C.

a. 8.4×107 m/s

b. 3.8×106 m/s

c. 6×106 m/s

d. 4.7×107 m/s