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
Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal?
An electrical bulb is marked 200V, 100W. Calculate the electrical resistance of its filament. If five such
bulbs are connected in series to a 200V supply, how much current will flow through them?
Name the unit of electrical resistance and give its symbol.
Ohm's law gives a relationship between:
(a) current and resistance
(b) resistance and potential difference
(c) potential difference and electric charge
(d) current and potential difference
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 resistors R1, R2, R3 and R4 in the figure given below are all equal in value.
What would you expect the voltmeter A, B and C to read assuming that the connecting wires in the circuit have negligible resistance?
- Draw a V-I graph for a conductor obeying Ohm’s law.
- What does the slope of V–I graph for a conductor represent?
An electric bulb draws 1.2 A current at 6.0 V. Find the resistance of filament of bulb while glowing.
Show by a diagram how two resistors R1 and R2 are joined in parallel. Obtain an expression for the total resistance of the combination.
In the circuit shown below in Fig, calculate the value of x if the equivalent resistance between A and B is 4 Ω.
A metal sphere is kept on an insulting stands. A negatively charged rod is brought near it, then the sphere is earthed as shown. On removing the earthing, and taking the negatively charged rod away, what will be the nature of charge on the sphere? Give reason for your answer.
Fig. represents the circuit used for the verification of ohm's law. Label the different parts from A and F. State the function of each.
State and define Ohm’s law.
Define ampere and volt with respect to Ohm’s law.
What are ohmic conductors? Give one exmaple. Draw a graph showing the current-voltage relationship for an ohmic conductor.
A wire connected to a power supply of 230 V has power dissipation P1. Suppose the wire is cut into two equal pieces and connected parallel to the same power supply. In this case, power dissipation is P2. The ratio of `"P"_2/"P"_1` is
What is non ohmic device?
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 I-V graph represents ohmic conductors?
The heat produced by a 100 w heater in 2 minute is equal to
Ohm's law deals with the relationship between ______
Suppose there is a circuit consisting of only resistances and batteries and we have to double (or increase it to n-times) all voltages and all resistances. Show that currents are unaltered. Do this for circuit of Example 3.7 in the NCERT Text Book for Class XII.
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.
What is meant by resistance of a conductor ? Define its SI unit.
A current of 0.8 A flows in a conductor of 40 Ω for 1 minute. The heat produced in the conductor will be ______.
A current of 3.2 mA flows through a conductor. If charge on an electron is −1.6 × 10-19 coulomb, find the number of electrons that will pass each second through the cross section of that conductor.
