The best material for the core of the primary and secondary coils of an induction coil is
copper, because it has a good conductor of electricity
steel, because it becomes magnetic and retains its magnetism for a long time
rubber, because it is a good insulator and the user is prevented from shock
soft iron, because it becomes magnetic but easily loses its magnetism
glass, because it is transparent
Correct answer is D
No explanation has been provided for this answer.
High Tension(H.T.) transmission means
to transmit a given amount of power, the tension in the conducting wire must be high
heat is not lost when current is passed through a conductor
heat is gained when a given power is transmitted
a big transformer is required to transmit power
trasmission of power at low current and high voltage
Correct answer is E
No explanation has been provided for this answer.
In sunlight, a blue flower looks blue because we see the flower by the light it
recieves from our eye
disperses
absorbs
refracts
reflects
Correct answer is E
No explanation has been provided for this answer.
there is only one lens
the objective lens have a shorter focal length than the eyepiece which is convex
the objective lens has a longer focal length than the eyepiece which is convex
the objective lens has a shorter focal length than the eyepiece which is concave
the objective and the eyepiece are both convex and have the same focal length
Correct answer is B
A compound microscope consists of two convex lenses: an objective lens O of small aperture and an eye piece E of large aperture. The lens which is placed towards the object is called objective lens, while the lens which is towards our eye is called eye piece. These two convex lenses i.e. the objective and the eye piece have short focal length and are fitted at the free ends of two sliding tubes at a suitable distance from each other. Although the focal length of both the objective lens and eye piece is short, but the focal length of the objective lens O is a little shorter than that of the eye piece E.
Which of the following statements about sound is NOT true?
sound is a longitudinal wave
sound can be reflected and refracted like light
sound travels through a vacuum
sound moves faster in a steel wire than in air
sound can ony be produced by vibrating objects
Correct answer is C
Sound cannot travel through a vacuum. A vacuum is an area without any air, like space. So sound cannot travel through space because there is no matter for the vibrations to work in.