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Physics Part-I
Class 12
NCERT
1
Chapter 1: Electric Charges and Fields
47 questions
2
Chapter 2: Electrostatic Potential and Capacitance
46 questions
3
Chapter 3: Current Electricity
33 questions
Q1
What conclusion can you draw from the following observations on a resistor made of alloy manganin?
Q2
Answer the following question:
(a) A steady current flows in a metallic conductor of non-uniform cross-section. Which of these quantities is constant along the conductor: current, current density, electric field, drift speed?
(b) Is Ohms law universally applicable for all conducting elements?If not, give examples of elements which do not obey Ohms law.
(c) A low voltage supply from which one needs high currents must have very low internal resistance. Why?
(d) A high tension (HT) supply of, say, 6 kV must have a very large internal resistance. Why?
Q3
Choose the correct alternative:
(a) Alloys of metals usually have (greater/less) resistivity than that of their constituent metals.(b) Alloys usually have much (lower/higher) temperature coefficients of resistance than pure metals.
(c) The resistivity of the alloy manganin is nearly independent of / increases rapidly with increase of temperature.
(d) The resistivity of a typical insulator (e.g., amber) is greater than that of a metal by a factor of the order of ().
4
Chapter 4: Moving Charges and Magnetism
41 questions
5
Chapter 5: Magnetism and Matter
36 questions
6
Chapter 6: Electromagnetic Induction
28 questions
7
Chapter 7: Alternating Current
37 questions
8
Chapter 8: Electromagnetic Waves
20 questions
Question
Medium
Solving time: 3 mins
Answer the following question:(a) A steady current flows in a metallic conductor of non-uniform cross-section. Which of these quantities is constant along the conductor: current, current density, electric field, drift speed?(b) Is Ohms law universally applicable for all conducting elements?If not, give examples of elements which do not obey Ohms law.(c) A low voltage supply from which one needs high currents must have very low internal resistance. Why?(d) A high tension (HT) supply of, say, 6 kV must have a very large internal resistance. Why?
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Text solution
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(a) Since current is given to be steady, it is constant. The current density, electric field and drift speed are inversely proportional to area of cross section.
(b) No, examples of non-ohmic elements are vacuum diode,semiconductor diode, etc.
(c) By Ohms Law, . Now, if current required is high, the voltage should be high and the resistance should be low. Hence, a low voltage supply from which one needs high currents must have very low internal resistance.
(d) Any high tension supply must have a large internal resistance, because, if the circuit is shorted (accidentally), the current drawn will exceed safety limits. This can be dangerous for human life and can cause fatal accidents.
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Practice more questions from Physics Part-I (NCERT)
Q1
What conclusion can you draw from the following observations on a resistor made of alloy manganin?
Q2
Answer the following question:
(a) A steady current flows in a metallic conductor of non-uniform cross-section. Which of these quantities is constant along the conductor: current, current density, electric field, drift speed?
(b) Is Ohms law universally applicable for all conducting elements?If not, give examples of elements which do not obey Ohms law.
(c) A low voltage supply from which one needs high currents must have very low internal resistance. Why?
(d) A high tension (HT) supply of, say, 6 kV must have a very large internal resistance. Why?
Q3
Choose the correct alternative:
(a) Alloys of metals usually have (greater/less) resistivity than that of their constituent metals.(b) Alloys usually have much (lower/higher) temperature coefficients of resistance than pure metals.
(c) The resistivity of the alloy manganin is nearly independent of / increases rapidly with increase of temperature.
(d) The resistivity of a typical insulator (e.g., amber) is greater than that of a metal by a factor of the order of ().
Practice questions from Physics Part-I (NCERT)
Question 1
Easy
Views: 6,525
(b) If the combination is connected to a battery of emf 20 V and negligible internal resistance, detere the current through each resistor, and the total current drawn from the battery.
Question 2
Medium
Views: 5,893
Choose the correct alternative:
(a) Alloys of metals usually have (greater/less) resistivity than that of their constituent metals.(b) Alloys usually have much (lower/higher) temperature coefficients of resistance than pure metals.
(c) The resistivity of the alloy manganin is nearly independent of / increases rapidly with increase of temperature.
(d) The resistivity of a typical insulator (e.g., amber) is greater than that of a metal by a factor of the order of ().
Practice more questions from Current Electricity
Question 1
Hard
Views: 5,405
(a) Are there positive and negative terminals on the galvanometer?
(b) Copy the figure in your answer book and show the battery and the galvanometer (with jockey) connected at appropriate points.
(c) After appropriate connections are made, it is found that no deflection takes place in the galvanometer when the sliding jockey touches the wire at a distance of from . Obtain the value of the resistance .
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| Question Text | Answer the following question: (a) A steady current flows in a metallic conductor of non-uniform cross-section. Which of these quantities is constant along the conductor: current, current density, electric field, drift speed? (b) Is Ohms law universally applicable for all conducting elements?If not, give examples of elements which do not obey Ohms law. (c) A low voltage supply from which one needs high currents must have very low internal resistance. Why? (d) A high tension (HT) supply of, say, 6 kV must have a very large internal resistance. Why? |
| Topic | Current Electricity |
| Subject | Physics |
| Class | Class 12 |
| Answer Type | Text solution:1 |
| Upvotes | 82 |
