Bakelite is used in making electrical appliances because it is a
good conductor of heat
good conductor of electricity
good insulator of electricity
thermoplastic
When electric current is passed through a metallic conductor, amount of heat produced in the conductor depends on its
material and thickness
material, length and thickness
material and length
length and thickness
Anjali asks the following tasks to be performed by students of Class VII while making an electromagnet (not in correct sequence).
(i) Place some pins near the end of a nail.
(ii) Switch on the current and observe what
(iii) Wind a copper 'wire tightly around an iron nail.
(iv) Connect free end of the wire to the terminals of a cell.
Which one of the following is the correct sequence of task to be performed to achieve the desired result?
(i), (ii), (iii), (iv)
(iii), (iv), (i), (ii)
(iii), (i), (ii), (iv)
(iv), (ii), (iii), (i)
Which is significant for a fuse wire?
Its melting point
Its specific resistance
Current flowing through it
All of the above
Which among the following liquids are conductors of electricity?
A, C and D
B and C
A and C
C and D
Which of the following facts is not correct about magnets?
The attraction is a sure test of magnetism
Magnetic field lines originate from North-pole and merge at South-pole of a magnet
Like poles of a magnet repel each other
The magnetic field is stronger at the poles of a bar magnet
Magnetic quantum number determines
shape of orbitals
orientation of orbitals
total energy of an-orbital
spin of an electron
Three-wire of resistance 1Ω, 2Ω, and 3Ω respectively are connected in 'parallel'. The equivalent resistance of the circuit is
6Ω