Advertisements
Advertisements
प्रश्न
Answer the following question.
Distinguish between Ohmic and non-ohmic substances; explain with the help of example.
Advertisements
उत्तर
| Ohmic substances | Non-ohmic substances |
| 1. Substances which obey ohm’s law are called ohmic substances | 1. Substances which do not obey ohm’s law are called non-ohmic substances. |
| 2. Potential difference (V) versus current (I) curve is a straight line. | 2. Potential difference (V) versus current (I) curve is not a straight line. |
| 3. Resistance of these substances is constant i.e. they follow linear I-V characteristic. | 3. Resistance of these substances is a function of V or I. |
| 4. Expression for resistance is, R = `"V"/"I"` | 4. Expression for resistance is, R = `lim_(Δ"l"→0)(Δ"V")/(Δ"I")="dV"/"dI"` |
| 5. Examples: Gold, silver, copper etc. | 5. Examples: Liquid electrolytes, vacuum tubes, junction diodes, thermistors etc. |
APPEARS IN
संबंधित प्रश्न
If the potential difference across the ends of a conductor is 220 V and the resistance of the conductor is 44 Ω (ohm), then the current flowing through is _________.
- 0.2 A
- 0.5 A
- 2 A
- 5 A
What will be the change in the current if the potential difference is kept constant and the resistance of the circuit is made four times?
- It will remain unchanged.
- It will become four times.
- It will become one-fourth.
- It will become half.
Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal?
What is Resistivity?
Find the expression for the resistivity of a material and state the SI unit of resistivity.
When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Calculate the value of the resistance of the resistor.
Keeping the p.d. constant, the resistance of a circuit is halved. The current will become:
(a) one-fourth
(b) four time
(c) half
(d) double
The graph between V and I for a conductor is a straight line passing through the origin.
Which law is illustrated by such a graph?
State Ohm’s law and draw a neat labelled circuit diagram containing a battery, a key, a voltmeter, an ammeter, a rheostat and an unknown resistance to verify it.
What is the necessary condition for a conductor to obey Ohm’s law?
In a conductor 6.25 × `10^16` electrons flow from its end A to B in 2 s. Find the current flowing through the conductor (e = 1.6 × `10^-19` C)
A wire of resistance 9 ohm having length 30 cm is tripled on itself. What is its new resistance?
Consider the sacle of voltmeter shown in the diagram and answer the following questions :
(a) What is the least count of the voltmeter?
(b) What is the reading shown by the voltmeter ?
(c) If the voltmeter is connected across a resistor of 20 `Omega` how much current is flowing through the resistor?
- Name and state the law which relates the potential difference and current in a conductor.
- What is the necessary condition for a conductor to obey the law named above in part (a) ?
Rewrite the following statement by selecting the correct option.
The S.I. unit of resistance is __________.
State the limitations of Ohm’s law.
What are ohmic conductors? Give one exmaple. Draw a graph showing the current-voltage relationship for an ohmic conductor.
Explain the equivalent resistance of a series resistor network.
Explain the equivalent resistance of a parallel resistor network.
The resistance of a nichrome wire at 0°C is 10Ω. If its temperature coefficient of resistivity of nichrome is 0.004/ °C, find its resistance of the wire at boiling point of water. Comment on the result.
Which of the following is correct for V-I graph of a good conductor?
Assertion: The statement of Ohm’s law is K = IR.
Reason: V = IR is the equation which defines resistance.
A heater of 220 V heats a volume of water m 5 mint time. A heater of 110 V heat in ten second. The resistance of the conductor is
You are provided with a resistor, a key, an ammeter, a voltmeter, four cells of 1.5 V each and few connecting wires. Using circuit components, draw a labelled circuit diagram to show the setup to study Ohm's law.
State the relationship between potential difference (V) across the resistor and the current (I) flowing through it. Also draw V-I graph, taking V on the X-axis.
How is electric current related to the potential difference across the terminals of a conductor?
Draw a labelled circuit diagram to verify this relationship.
The voltage - current readings of a certain material are shown in the table given below:
| Voltage (V) | 10 V | 20 V | 30 V |
| Current (I) | 2 A | 3 A | 4 A |
Study the table.
- State whether the conductor used is ohmic or non-ohmic.
- Justify your answer.
- State Ohm's law.
