Consider a circular loop of wire lying in the plane of the table. Let the current pass through the loop clockwise. Apply the right-hand rule to find out the direction of the magnetic field inside and outside the loop.
Inside the loop = Pierce inside the table
Outside the loop = Appear to emerge out from the table
For the downward direction of current flowing in the circular loop, the direction of magnetic field lines will be as if they are emerging from the table outside the loop and merging in the table inside the loop. Similarly, for the upward direction of current flowing in the circular loop, the direction of magnetic field lines will be as if they are emerging from the table outside the loop and merging in the table inside the loop, as shown in the given figure.
The magnetic field in a given region is uniform. Draw a diagram to represent it.
How does a solenoid behave like a magnet? Can you determine the north and south poles of a current–carrying solenoid with the help of a bar magnet? Explain.
Explain the underlying principle and working of an electric generator by drawing a labelled diagram. What is the function of brushes?
In Activity 13.7, how do we think the displacement of rod AB will be affected if (i) current in rod AB is increased; (ii) a stronger horse-shoe magnet is used; and (iii) length of the rod AB is increased?
A positively-charged particle (alpha-particle) projected towards west is deflected towards north by a magnetic field. The direction of magnetic field is
(a) towards south (b) towards east
(c) downward (d) upward
Draw a labelled diagram of an electric motor. Explain its principle and working. What is the function of a split ring in an electric motor?
Draw magnetic field lines around a bar magnet.
Two circular coils A and B are placed closed to each other. If the current in the coil A is changed, will some current be induced in the coil B? Give reason.
List the properties of magnetic field lines.
State Fleming’s left-hand rule.
Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.
What is a good source of energy?
Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
What changes can you make in your habits to become more environment-friendly?
What is the difference between a reflex action and walking?
What is the importance of DNA copying in reproduction?
If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?
Why should a magnesium ribbon be cleared before burning in air?
Define the principal focus of a concave mirror.
What effect does the concentration of H+(aq) ions have on the nature of the solution?
The autotrophic mode of nutrition requires
(a) carbon dioxide and water. (c) sunlight.
(b) chlorophyll. (d) all of the above.
Besides gallium, which other elements have since been discovered that were left by Mendeléev in his Periodic Table? (any two)
How do Mendel’s experiments show that traits may be dominant or recessive?
Draw the structure for the following compounds.
(i) Ethanoic acid (ii) Bromopentane*
(iii) Butanone (iv) Hexanal.
*Are structural isomers possible for bromopentane?
What are alloys?
The kidneys in human beings are a part of the system for
(a) nutrition. (c) excretion.
(b) respiration. (d) transportation.
What is the role of decomposers in the ecosystem?
What does an electric circuit mean?
Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).