The diagram Fig.12 shown a piece of pure semiconductor S in series with a variable resistor R, and a source of constant voltage V. Would you increase or decrease the value of R to keep the reading of ammeter constant, when semi-conductor S is heated? Give reason.

A 6 V, 12 W lamp is connected in series with a resistor R and a source of voltage 12 V. Calculate the value of the resistor R, for the proper working of the lamp.

A constant voltage V_(0) is applied to a potentiometer of resistance R connected to an ammeter. A constant resistor r is connected to the sliding contact of the potentiometer and the fixed end of the potentiometer. If the reading of ammeter vary as the sliding contact is moved from one end of the potentiometer to the other. The resistance of ammeter is assumed to be negligible. Find the minimum reading of the Ammeter.

A voltmeter is connected in parallel with a variable resistance R which is in series with an ammeter and a cell as shown in the figure . For one value of R=2Ω,the reading are 0.25A and 1.0 V. What is the internal resistance of the cell ?

Assertion : If the radius of earth is decreased keeping its mass constant, effective value of g may increase or decrease at pole. Reason : Value of g on the surface of earth is given by g= (Gm)/(R^(2)) .

The diagram shows a capacitor C and a resistor R connected in series to an ac source. V_1 and V_2 are voltmeters and A is an ammeter. Consider the following statement I. Reading n A and V_2 are always in phase II. Reading in V_1 is ahead in phase with reading in V_2 III. reading in Aand V_1 are always in phase. which of these statments is/are correct

In an electric iron heat producedm is same, whether it is connected across an A.c. source or across 50 V constant voltage. R.M.S. value of the A.C. voltage applied is

The diagram in Fig. shows a cell of e.m.f. epsi = 2 volt and internal resistance r = 1 ohm connected to an external resistance R = 4 ohm. The ammeter A measures the current in the circuit and the voltmeter V measures the terminal voltage across the cell. What will be the readings of the ammeter and voltmeter when the key K is open

The diagram in Fig. shows a cell of e.m.f. epsi = 2 volt and internal resistance r = 1 ohm connected to an external resistance R = 4 ohm. The ammeter A measures the current in the circuit and the voltmeter V measures the terminal voltage across the cell. What will be the readings of the ammeter and voltmeter when the key K is closed.

The circuit diagram shown in Fig includes a 6 V battery, an ammeter A, a fixed resistor R_I of 2 Omega and a resistance wire R_2 connected between the terminals A and B. The resistance of the battery and ammeter may be neglected. Calculate the ammeter readings when the wire R_2 is of 0.20 m length and of area of cross section double than that in case (a).

The circuit diagram shown in Fig includes a 6 V battery, an ammeter A, a fixed resistor R_I of 2 Omega and a resistance wire R_2 connected between the terminals A and B. The resistance of the battery and ammeter may be neglected. Calculate the ammeter readings when the wire R_2 is of 0.20 m length and of resistance 4 Omega .