A step-up transformer is placed between a power station and a long-distance electricity transmission cable. What is the role of the step-up transformer, and does it work with alternating current (a.c.) or with direct current (d.c.)?
- Ato decrease the current in the cable, d.c.
- Bto decrease the current in the cable, a.c.
- Cto increase the current in the cable, d.c.
- Dto increase the current in the cable, a.c.