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The level of electric charge present is known as potential.

• Copper and aluminum are good conductors of electricity. 
• They have low electrical resistance and large number of free electrons. 
• As they are malleable and ductile, they can be drawn into thin wires. Hence, connecting wires in a circuit are made of copper or aluminum.

A. low resistivity

 The symbol given for ohm is Ω.

Total resistance

When a battery is connected to a series circuit, it delivers current based only upon total resistance

The correct option is : D. Voltage

Voltmeter is always connected in parallel. 

The correct option is: B. Half

if the resistance is doubled then the current will be i=v/2r

D. Any of the above

D. Current doubles and resistance remains the same.

Semi-insulators, which sometimes conduct and sometimes insulate

In an atom, the free electrons are present at outermost orbit. It can easily ow from one atom to another by applying voltage. So it is called as conductor.

Current

Current remains same in series circuit and changes in parallel circuit.

Rheostat = Variable resistance.

A. R₁ + R₂ + R₃

A. it will repel each other

A. no resistance

Electrons in the outer orbit are called valences.

B. conductance

1/R = (1/430 + 1/210 + 1/100) 

R = 58.82 ohm

r₁+r₂+r₃=R 

1.4 +1.4 + X=12 

x=9.2 Kilo ohm 

9200 ohm

V₁-V₂ (i.e): 24-10=14v.

Increases

When the resisters are connected in series resistance of the circuit will be more than the resisters are connected in parallel. Parallel resistor is removed from the circuit the resistance will increase. 

Series means current is same so all resistors are added 140 + 250 + 220 = 610

When Switch is closed in any circuit it acts as a closed circuit so current flows only in a closed circuit.

When resistance decreases, the current increases. Because R=V/I, resistance and current are inversely proportional. 

1 coulomb is the charge carried by 6.25*10¹⁸ electrons.

A. Appliances are connected in parallel.

B. The potential difference across all appliances is same in parallel connection.

C. No, as every appliance has a different load (resistance), the current flowing through each appliance will be different.

D. The domestic appliances are connected in parallel as the potential difference remains same.

E. No, the other devices will not stop working as the current flowing through them is along different paths.

(a) R₁ = 6 ohm

R₂ = 4 ohm

R = R₁ + R₂ = 6 + 4 = 10 ohm

V = 20 V

I = V/R = 20/10 = 2 A

(b) R = 6 W

I = 2 A

V = ?

V = IR = 6 × 2 = 12 V

For the same change in I, change in V is less for the straight line A than for the straight line B (i.e., the straight line A is less steeper than B), so the straight line A represents small resistance, while the straight line B represents more resistance. In parallel combination, the resistance decreases while in series combination, the resistance increases. So A represents the parallel combination.

For resistor A:

R = 1 ohm

V = 2 V

I = V/R = 2/1 = 2A

For resistor B:

R = 2 ohm

V = 2 V

I = V/R = 2/2 = 1A

In series combination of resistances, current is same in each resistance.

Hint: In a series combination, the current has a single path for its flow. Hence, the same current passes through each resistor.

In parallel combination of resistances, P.D. is same across each resistance.

Hint: In parallel combination, the ends of each resistor are connected to the ends of the same source of potential. Thus, the potential difference across each resistance is same and is equal to the potential difference across the terminals of the source (or battery).

(a) and (d)

Solution:

In fig (a), the resistors are connected in parallel

Between X and Y.

Let ' R be their equivalent resistance.

Then , 1/R = 1/2 + 1/2 = 2/2 Ω

Or, R^I = 1 Ω ………………. (i)

In fig (d) a series combination of two 1 Ω resistors Is in parallel with another series combination of two 1Ω resistors

Series resistance of two 1 Ohm resistors,

R= (1 + 1) Ω = 2 Ω

Thus, we can say that across X and Y, two 2 Ω resistors are connected in parallel

Let ' R be the net resistance across X and Y.

Then, 1/R = 1/2 + 1/2 = (2/2)Ω

Or, ' R = 1 Ω ……………………(ii)

From (i) and (ii), it is clear that (a) and (d) have

The same equivalent resistance between X and Y.

ε = 3 volt

I = 1.5 A

V = 2.7 V

V = ε − Ir

r = (e-V) / I

= (3 – 2.7) / 1.5 = 0.2 ohm

In parallel R = ½ + ½ = 1 ohm

I = 1.2 A

ε = I(R + r) = 1.2(1 + r) = 1.2 + 1.2 r

In series R = 2+2 = 4 ohm

I = 0.4 A

ε = I(R + r) = 0.4(4 + r) = 1.6 + 0.4 r

It means :

1.2 + 1.2 r = 1.6 + 0.4 r

0.8 r = 0.4

r = 0.4 / 0.8 = ½ = 0.5 ohm

(i) Internal resistance r = 0.5 ohm

(ii) ε = I(R+r) = 1.2(1+0.5) = 1.8 V

When n resistors are in series, \(I=\frac{E}{R+nR};\)

When n resistors are in parallel, \(\frac{E}{R\,+\,\frac{R}{n}}=10I\)

\(\frac{1+n}{1+\frac{1}{n}}=10\) 

\(\Rightarrow\,\,\frac{1+n}{n+1}n=10\)  \(\Rightarrow\,n=10.\)

(i) Vaikunth : Acknowledging the help from others with gratitude.

(ii) Vasu : Awareness of the technology, helping tendency and practical knowledge of the subject.

(iii) Electric fuse is a safety device that carries a tungsten wire which gets melts due to high current flow that has low melting point and high resistivity

It is used to determine the unknown resistance of a given coil. 

It works on the principle of balanced condition of whetstone’s network. 

The error in finding R in a meter bridge can be minimized by adjusting the balancing point near middle of the bridge (close to 50 cm) by suitable choice of standard resistance S. 

It is an instrument consisting of long piece of uniform wire across which a standard cell is connected. 

B. electrical, mechanical, light, heat, magnetic, and chemical

The finite resistance offered by the electrolyte for the flow of current through it is called internal resistance. 

To convert a moving-coil galvanometer (MCG) into an ammeter, the following modifications are necessary :

1. The effective current capacity of the MCG must be increased to a desired higher value. 

2. A galvanometer when connected in series with a resistance, should not decrease the current through the resistance. Hence, the effective resistance of the galvanometer must be decreased by connecting an appropriate low resistance across it. An ideal ammeter should have zero resistance. 

3. It must be protected from the damages which are likely to occur due to the passage of an excess electric current.

Applying Kirchhoff's loop rule for loop ABEFA,

9 + 6 + 4 × 0 + 2I = 0

I = 1.5 A       ...(i)    

For loop BCDEB

3 + IR + 4 × 0 – 6 = 0

∴ IR = 3

Putting the value of I from (i) we have

\(\frac{3}{2}\times R=3\) \(\Rightarrow R=2\Omega\)

Potential difference between A and D through path ABCD

9 - 3 - IR = VAD

or  9 - 3 - \(\frac{3}{2}\times 2\) = V_AD \(\Rightarrow\) V_AD = 3V

(i) Thermometer

(ii) Rubber

(iii) Steel

(iv) Fullerenes

Electric cell is a device which converts energy from electrical to chemical.

Answer is 9/6 = 1.5V

Answer is 100/10 = 10V