An electron accelerated through 30-kV, in a cathode ray oscilloscope, enters a system of deflecting plates. The deflecting field between the plates is 24 kV m−1. The length of the deflecting plates is 0.06 m and the total deflection produced in the path of the electron on a screen is 9 mm.What is the distance of the screen from the near end of the plates?
0.35 m
0.38 m
0.40 m
0.45 m
Two charges of amount +5 µC and −5 µC are located 0.05 cm apart from each other form an electric dipole. The dipole is held at an angle of 60° in a uniform electric field of 2.1 × 105 N C−1. What is the value of the torque acting on the dipole ?
2.1 × 10−4 N m
4.5 × 10−4 N m
7.2 × 10−4 N m
9.1 × 10 -4 N m
There are three charges, , placed along a straight line of length 10 m, as shown in the given figure.
What is the net electrostatic force acting on charge q2?
12 × 10−3 N towards q1
28.5 × 10−3 N towards q1
12 × 10−3 N towards q3
28.5 × 10−3 N towards q3
The electric field intensity of a point P at a distance of 0.30 m from the centre of a Gaussian charged sphere of radius 0.20 m is 2.5 × 103 N C-1, directed radically outwards. What is the electric flux emanating through the given Gaussian surface?
2.82 × 103 N m2C-1
1.25 × 103 N m2C-1
0.63 × 103 N m2 C-1
0.31 × 103 N m2C-1
Two charged balls are suspended from a hinge by two threads of equal lengths. Mass of both the balls is 200 g. The amount of charges on both the balls is the same. At translational equilibrium, the balls are separated by a distance of 0.8 m, as shown in the given figure. What is the magnitude of charge on each ball?
4.33 µC
8.97 µC
17.16 µC
34.48 µC
The bob of a pendulum of mass 100 g is at equilibrium in a horizontal uniform electric field of 2.5 × 105 V m−1. In this equilibrium position, the pendulum makes an angle with the vertical. The amount of charge on the bob is 3 µC. Assume that the bob is suspended by means of a thin mass-less string. What will be the tension in the string when the bob is at equilibrium?
0.75 N
1.23 N
0.75 × 102 N
1.23 × 102 N
Two charges, +2 µC and +8 µC, are placed 0.1 m apart. Another charge is placed between the two, which brings the system in equilibrium.What is the magnitude of the third charge?
0.75 µC
0.87 µC
2.50 µC
1.25 µC
Two charged particles are located at a distance of 1.5 m. The force of attraction between the charges is 2.1 × 10−7 N. One particle has a charge equal to two thirds the charge of another particle. What is the value of charges on the two particles?
A positive charge q is placed at the centre of a cube. A side of the cube is 0.2 m. The electric flux through each Gaussian surface of the cube is 4.708 × 104 N m2 C−1. What is the value of charge q ?
1 μC
1.5 μC
2.5 μC
3 μC
A charge experiences a force of 32 N as it is placed at a certain distance on the axial line of an electric dipole.What will be the force on the charge if its distance from the dipole is halved?
64 N
128 N
256 N
512 N
