Ohm's Law

Q.

What are the limitations of Ohms Law?

Q.

What is the difference Between Metals, Insulators, and Semiconductors on the basis of their energy bands?

Q. In the electric circuit given below, the reading of ammeter is

1. 2 A
2. 1 A
3. 3 A
4. 4 A

Q. Derive the SI Unit of resistivity

Q.

Masses of three wires of copper are in the ratio 1 : 3 : 5 and their lengths are in the ratio of 5 : 3 : 1. The ratio of their electrical resistances are ___ .

1. 1 : 3 : 5

2. 5 : 3 : 1

3. 1 : 15 : 125

4. 125 : 15 : 1

Q.

State Ohm’s law. [1 MARK]

Q. Let the resistance of an electrical component remains constant while the potential difference across the two ends of the component decreases to half of its former value. What change will occur in the current through it?

Q.

Calculate the resistance of a metal wire of length 2m and area of cross-section $1.55\times {10}^{-6}{m}^2$ , if the resistivity of the metal be $2.8\times {10}^{-8}$ Ωm?

Q.

An electric circuit consisting of a 0.5 m long nichrome wire XY, an ameter, a voltmeter four cells of 1.5 V each and a plug key was set up.
(i) Draw a diagram of this electric circuit to study the relation between the potential difference maintained between the points 'X' and 'Y' and the electric current flowing through XY.
(ii) Folloiwng graph was plotted between V and I values:
What would be the values of $\frac{V}{I}$ ratios when hte potential difference is 0.8 V, 1.2 V and 1.6 vrespectively ?
What conclusion do you draw from these values?

What would be hte values of $\frac{V}{I}$ ratios when the potential differece is 0.8 V, 1.2 V and 1.6 V respectively what conclusion do you draw from these values?
(iii) What is the resistance of the wire?

Q. Question 10
How many $176\Omega$ resistors (in parallel) are required to carry 5 A on a 220 V line?

Q. What is heating effect of electric current?

Q.

A 4 ohm wire is doubled on it. Calculate the new resistance of the wire.

Q.

An electric kettle takes $4A$ current at 220V. How much time will it take to boil $1kg$ of water from room temperature $20{}^{o}C$? (The temperature of boiling water is $100{}^{o}C$).

Q.

Name two factors on which the internal resistance of a cell depends and state how does it depend on the factors stated by you.

Q.

What is ohm's law? Explain how it is used to define the unit of resistance.

Q.

(a) Draw a V-I graph for a conductor obeying Ohm's law.

(b) What does the slope of V-I graph for a conductor represent?

Q. Derivation of joule's law of heating

Q.

What is the relationship between current and resistance

Q.

What happens to voltage when resistance decreases?

Q.

Calculate the resistivity of a wire of length 1m and 0.01cm and resistance 20ohm

Q. A current of 200 Milli ampere flows through 4 k ohm resistance. What is the potential difference across the resistor?

Q.

Name the unit of electrical resistance and give its symbol.

Q.

Thermal resistivity is the ___of thermal conductivity.

Q.

Calculate the resistance of an aluminum cable of length 10km and diameter 2.0mm if the resistivity is 2.7x10^-8 Ohm-meter

Q.

If voltage $V=\left(100\pm 5\right)V$ and current $I=\left(10\pm 0.2\right)A$, the percentage error in resistance $R$ is:

1. $5.2\%$

2. $25\%$

3. $7\%$

4. $10\%$

Q.

State the factors on which the strenth of electric current flowing in a given conductor depends.

Q.

A coil of inductance $300mH$ and resistance $2\Omega$ is connected to a source of voltage $2V$. The current reaches half of its steady-state value in.

1. $0.15sec$

2. $0.3sec$

3. $0.05sec$

4. $0.1sec$

Q.

Draw a I - V graph for a linear resistor. What does its slope represent?

Q.

In an experiment of verification of Ohm's law, following observations are obtained.
$$\begin{array}{cccccc}\text{Potential difference V (in Volt)}& 0.5& 1.0& 1.5& 2.0& 2.5\\ \text{Current I (in ampere)}& 0.2& 0.4& 0.6& 0.8& 1.0\end{array}$$
Draw a V- I graph and use this graph to find :
(a) the potential difference V when the current I is 0.5 A,
(b) the current I when the potential difference V is 0.75 V,
(c) the resistance in circuit.

Q.

Statement I- The voltage across a resistance is directly proportional to the current flowing in it.

Statement II- Ohm’s law

1. Statement 1 is true and statement 2 defines it

2. Data insufficient

3. Statement 1 is true but statement 2 doesn’t define it

4. Statement 1 is false