1. Which of the following statements is / are correct about magnetic induction? I. It results in mutual attraction between the bodies concerned.

II. Adjacent parts of the bodies involved have OPPOSITE polarity.

III. When in use, keepers for storing magnets are magnetised by induction.

a
I , II and III
b
I only
c
I and III only
d
I and II only
2. What is the purpose of a magnetic relay?

a
To use a small current to switch on a larger current
b
To use a large current to switch on a small current
c
To change a small voltage into a larger voltage
d
To change a large voltage into a smaller voltage
3. The diagram shows the apparatus that can be used to make a magnet.

Which metal and which power supply are used to make a permanent magnet?

a
Steel and a 6v d. c. supply
b
Iron and a 6v a. c. supply
c
Iron and a 6v d. c. supply
d
Steel and a 6v a. c. supply

Dax dxsadccgcnschbcjchbcgbcn bhc

Answer: a charge of -1.0  × 10⁻⁴ c must be placed  at x = 26 m.the sign of the charge will be the same sign as the  -4.0  µc charge.======electricstatic force between two point charges  is given by    where k is coulomb's constant,  8.99×10⁹  n·m²/c², q₁ and q₂ are the point charges, and r is the distance between the two point charges.assign positive to q₁let q₁ =  6.0 µc, q₂ = -4.0  µc, q₀ represent the charge at the origin, and q₃ represent this new charge to place.the charge at the origin q₀ would experience the following force f₀₁ from q₁, with r = 6.0 m (note that 1  µc = 10⁻⁶ c)    the force from q₂    the force from q₃    the net force on the origin charge, q₀, has to be zero for no electrostatic forcehaving an equation where k and q₀ can be divided out of the equation will allow us to solve for q₃    isolating:     a charge of -1.0  × 10⁻⁴ c must be placed  at x = 26 m.the sign of the charge will be the same as the  -4.0  µc charge