Which type of metal or alloy cannot be used to prepare a fuse wire?

Which instrument is used to know the presence of an electric current in a circuit?

You have just paid the electricity bill for your house.
$(i)$ What was it that your family consumed,for which you had to pay?
$(ii)$ In what unit was it measured?

$(a)$ An electric current is passed in a horizontal copper wire from east to west. Explain your observations when a compass needle is placed $(i)$ below this wire,$(ii)$ above the wire. Draw inference from your observations.
$(b)$ List the factors on which the strength of the magnetic field due to a straight conductor carrying current depend. How should these be changed to decrease magnetic field at a point?

Which of the following is used in a fire alarm?

An electric generator works on the principle of electromagnetic induction.