Read the following and answer any four questions. 

Connect a nichrome wire of length "L" between points X and Y in the provided circuit, and then record the ammeter reading. 

(a) What change in the ammeter reading is seen when this experiment is performed with the replacement of nichrome wire which is of the same thickness but twice its length (2L)? 

(i) Ammeter reading will become half 

(ii) Ammeter reading will double. 

(iii) Ammeter reading will increase three times 

(iv) Ammeter reading will become three-fourths 

(b) Explain how the ammeter reading would vary in the experiment above if the cross-area section was doubled without changing its length. In both situations, justify your response.  

(i) Ammeter reading will become half 

(ii) Ammeter reading decreases two times 

(iii) Ammeter reading will become three-fourths 

(iv) None of these 

(c) If two resistors with values of 3Ω and 6Ω are connected in series, the circuit. How will the currents passing through the two resistors vary? 

(i) Current will remain the same. 

(ii) Current will increase 2 times. 

(iii) Current will decrease 2times 

(iv) None of these. 

(d) What is the name of the instrument used to measure current? 

(i)  Voltmeter 

(ii)  Galvanometer 

(iii)  Photometer 

(iv)  Ammeter 

(e) In an electric field, there is a potential difference of 1 'V' between points X and Y. Describe the above statement. 

(a) When the length is increased to 2L, resistance increases, so the current decreases. Hence the ammeter reading will decrease.

$\mathrm{R}=\mathrm{\rho l}/\mathrm{A}\text{ will change to }2\mathrm{\rho l}/\mathrm{A}$

When $\rho$and A are constant, and L increases to 2L, resistance will increase twice the initial value. 

V = IR 

When resistance doubles, the current I will be halved at its original value. 

Hence option (i) Ammeter reading will become half, is correct. 

(b) When the cross-section area is doubled to 2A, resistance decreases by half as p and L are constant. 

$\mathrm{R}=\mathrm{\rho L}/\mathrm{A}\text{ will change to }\mathrm{\rho L}/2\mathrm{A}$

V = IR 

When resistance is halved, the current will double. 

The ammeter reading will increase to double the initial value. 

Hence option (ii) Ammeter reading decreases two times, is correct. 

(c) 

• Two or more resistors are said to be connected in series if they are connected end to end consecutively in an electric circuit.
• In a series circuit, the same amount of current passes through each resistor. 
• In such a connection, the potential drop across each resistor differs when all resistors have different resistance. 
• Hence, if two resistors of 3 Ω and 6 Ω are connected in series, the current passing through each of them is the same, and hence the ratio of current flowing through them is 1: 1.

So, the ratio of current flowing through them is 1:1.

Hence option (i) Current will remain the same is correct. 

(d) An instrument used to measure electric current is called an ammeter. The instrument displays the current passing through it in amperes; thus, the name is the ammeter. Generally, the instrument's resistance is very small, and thus there is less voltage drop across the instrument. This instrument is connected to other instruments we want to measure the current.

Hence option (iv) Ammeter is correct.

(e) The potential difference between points X and Y in an electric field is 1 volt, which means1 a joule of work is done to bring 1 coulomb of electric charge from point A to point B or from point B to point A. SI unit of potential difference is volt V.