Question no.3: A parallel-plate capacitor has plates of area 0.12 m2 and a separation of 1.2 cm. A battery charges the plates to a potential dif- ference of 120 V and is then disconnected. A dielectric slab of thick- ness 4.0 mm and dielectric constant 4.8 is then placed symmetrically between the plates. (a) What is the capacitance before the slab is inserted? (b) What is the capacitance with the slab in place? What is the free charge q (c) before and (d) after the slab is inserted? What is the magnitude of the electric field (e) in the space between the plates and dielectric and (f) in the dielectric itself? (g) With the slab in place, what is the potential difference across the plates? (h) How much external work is involved in inserting the slab?

Question

Question no.3:

A parallel-plate capacitor has plates of area 0.12 m2
and a
separation of 1.2 cm. A battery charges the plates to a potential dif-
ference of 120 V and is then disconnected. A dielectric slab of thick-
ness 4.0 mm and dielectric constant 4.8 is then placed symmetrically
between the plates. (a) What is the capacitance before the slab is
inserted? (b) What is the capacitance with the slab in place? What is
the free charge q (c) before and (d) after the slab is inserted? What
is the magnitude of the electric field (e) in the space between the
plates and dielectric and (f) in the dielectric itself? (g) With the slab
in place, what is the potential difference across the plates? (h) How
much external work is involved in inserting the slab?