A circuit has a resistance of 12 Ω and an impedance of 15 Ω. The power factor of the circuit will be
0.8
0.4
1.25
1.25
The phase difference between the alternating current and emf is π/2. Which of the following cannot be the constituent of the circuit?
C alone
R.L
L.C
L.C
A uniform electric field and a uniform magnetic field are acting along the same direction in a certain region. If an electron is projected along the direction of the fields with a certain velocity then
its velocity will decrease.
its velocity will increase.
it will turn towards right of direction of motion.
it will turn towards right of direction of motion.
A.
its velocity will decrease.
A charged particle of mass m and charge q travels on a circular path of radius r that is perpendicular to a magnetic field B. The time taken by the particle to complete one revolution is
In a potentiometer experiment, the balancing with a cell is at length 240 cm. On shunting, the cell with a resistance of 2Ω the balancing length becomes 120 cm. The internal resistance of the cell is
1 Ω
0.5 Ω
3 Ω
3 Ω
The resistance of hot tungsten filament is about 10 times the cold resistance. What will be the resistance of 100 W and 200 V lamp when not in use?
40 Ω
20 Ω
400 Ω
400 Ω
A magnetic needle is kept in a non-uniform magnetic field. It experiences
a torque but not a force
neither a force nor a torque
a force and a torque.
a force and a torque.
40.5 pF
Two sources of equal emf are connected to an external resistance R. The internal resistances of the two sources are R1 and R2 (R2>R1). If the potential difference across the source having internal resistance R2 is zero, then
R = R2-R1