Electrostatics — Physics STD 12 Science — Question

the anode is kept at positive potential with respect to the cathode:

Which one of the following properties of an element is not variable?

A current I is passing through a wire having two sections P and Q of uniform diameters d and d/2 respectively.  If the mean drift velocity of electrons in sections P and Q is denoted by v_P and v_Q respectively, then

(a) vP = vQ

(b) vP =  vQ

(c) vP =  vQ

(d) vP = 2 vQ

Assertion : V-i characteristic of P-N junction diode is same as that of any other conductor.

Reason     : P-N junction diode behave as conductor at room temperature.

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

If a power of 100 W is being supplied across a potential difference of 200 V, current flowing is

(a) 2 A

(b) 0.5 A

(c) 1 A

(d) 20 A

For measurement of potential difference, potentiometer is preferred in comparison to voltmeter because

(a) Potentiometer is more sensitive than voltmeter

(b) The resistance of potentiometer is less than voltmeter

(c) Potentiometer is cheaper than voltmeter

(d) Potentiometer does not take current from the circuit

A beam consisting of protons and electrons moving at the same speed goes through a thin region in which there is a magnetic field perpendicular to the beam. The protons and the electrons:

1. Will go undeviated.
2. Will be deviated by the same angle and will not separate.
3. Will be deviated by different angles and hence separate.
4. Will be deviated by the same angle but will separate.

The refractive index of water is 1.33. What will be the speed of light in water

(a) 3

(b) 2.25

(c) 4

(d) 1.33

In the figure a capacitor is filled with dielectrics. The resultant capacitance is

(a)

(b)

(c) []

(d) None of these

In the following Wheatstone bridge P/Q = R/S. If key K is closed, then the galvanometer will show deflection

(a) In left side

(b) In right side

(c) No deflection

(d) In either side