The free set of NCERT important questions carries step-by-step explanation and solution. Our science subject experts with years of experience have studied the CBSE exam patterns very carefully and come up with these set of questions based on the current CBSE syllabus.
CBSE NCERT Solutions for Class 7 Science Chapter 14:
Quest: Fill in the blanks:
(a) Longer line in the symbol for a cell represents its _____ terminal.
(b) The combination of two or more cells is called a ______
(c) When current is switched ‘on’ in a room heater, it _______
(d) The safety device based on the heating effect of electric current is called a _____.
(a) Longer line in the symbol for cell represents its positive terminal.
(b) The combination of two or more cells is called a battery.
(c) When current is switched 'on' in a room heater, it heats up.
(d) The safety device based on the heating effect of electric current is called a electric fuse.
Mark ‘T’ if the statement is true and ‘F’ if it is false:
(a) To make a battery of two cells, the negative terminal of one cell is connected to the negative terminal of the other cell. (T/F)
(b) When the electric current through the fuse exceeds a certain limit, the fuse wire melts and breaks. (T/F)
(c) An electromagnet does not attract a piece of iron. (T/F)
(d) An electric bell has an electromagnet. (T/F)
(a) F (b) T (c) F (d) T
Do you think an electromagnet can be used for separating plastic bags from a
garbage heap? Explain.
No, an electromagnet can be used for separating plastic bags from a garbage heap.
Since plastic bags are non-magnetic material and electromagnet is used to seperate only the magnetic materials.
An electrician is carrying out some repairs in your house. He wants to
replace a fuse by a piece of wire. Would you agree? Give reasons for your response.
No, I will not agree with the electrician. The wire use for making fuse have low
melting point and therefore any wire cannot be used to replace the fuse. In most cases, the ordinary wires have high melting point.