A Daniel cell is balanced on 125 cm length of a potentiometer wire. When the cell is short circuited with a 2 Ω resistance, the balancing length obtained is 100 cm. Internal resistance of the cell will be
(a) 1.5 Ω
(b) 0.5 Ω
(c) 1.25 Ω
(d) 4/5 Ω
(a) 1.5 Ω
(b) 0.5 Ω
(c) 1.25 Ω
(d) 4/5 Ω
(b) 0.5 Ω
A new flashlight cell of emf 1.5 volts gives a current of 15 amps, when connected directly to an ammeter of resistance 0.04 Ω. The internal resistance of cell is
(a) 0.04 Ω
(b) 0.06 Ω
(c) 0.10 Ω
(d) 10 Ω
In meter bridge, the balancing length from left end when standard resistance of 1 Ω is in right gap is found to be 20 cm. The value of unknown resistance is
(a) 0.25 Ω
(b) 0.4 Ω
(c) 0.5 Ω
(d) 4 Ω
Five resistances are combined according to the figure. The equivalent resistances between the points X and Y will be
(a) 10 Ω
(b) 22 Ω
(c) 20 Ω
(d) 50 Ω
A network of resistors is connected to a 16 V battery with internal resistance of 1Ω as shown in the Fig. Compute the equivalent resistance of the network.
(a) 5 ohm
(b) 7 ohm
(c) 9 ohm
(d) 10 ohm
A torch bulb rated as 4.5 W, 1.5 V is connected as shown in the figure. The emf of the cell needed to make the bulb glow at full intensity is
(a) 4.5 V
(b) 1.5 V
(c) 2.67 V
(d) 13.5 V
The V-i graph for a conductor at temperature T¹ and T² are as shown in the figure. (T² - T¹) is proportional to
(a) cos θ
(b) sin θ
(c) cot 2θ
(d) tan θ
A battery of emf 10 V and internal resistance 3 ohm is connected to a resistor. If the current in the circuit is 0.5 A, find :
(i) the resistance of the resistor;
(ii) the terminal voltage of the battery.
Two currents loops are concentric and lie in the same plane. The current in the outer loop is anti clockwise and increasing with time. The induced current in the inner loop ,is
(a) Clockwise
(b) Zero
(c) Counter-clockwise
(d) None of these
When light suffers reflection at the interface between water and glass, the change of phase in the reflected wave is
(a) zero..
(b) π.
(c) π/2.
(d) 2π.
If distance between two current- carrying wires is doubled, then force between them is
(a) halved
(b) doubled
(c) tripled
(d) quadrupled.
For sustained interference, we need two sources which emit radiations:
(a) of the same intensity
(b) of the same amplitude
(c) having a constant phase difference
(d) None of these
When a soap bubble is given an electric charge
(A) It contracts
(B) It expands
(C) Its size remains the same
(D) It expands or contracts depending upon whether the charge is positive or negative
The parameter of light wave which remain same after refraction
(A) speed
(B) frequency
(C) wavelength
(D) none of these
There is a uniform magnetic field directed perpendicular and into the plane of the paper. An irregular shaped conducting loop is slowly changing into a circular loop in the plane of the paper. Then,
(a) Current is induced in the loop in the anti-clockwise direction
(b) Current is induced in the loop in clockwise direction
(c) AC Current is induced in the loop
(d) No current is induced in the loop