Lightning is actually a sudden discharge of high voltage and high current arisiing out of large viltage(potential) differences between charged clouds. These surges, in their path towards the earth, can strike power lines and antennae and pass through the wires to the terminal equipment such as TV. The huge currents and voltages, even though of short life, can damage the electrical components and electronic circuits which are usually designed for low power. The surges are so powerful that they can destroy the equipment even if they are off but connected to the mains/antenna

Lightning is a sudden discharge of high voltage and high current arising between charged clouds. These surges, in their path towards the earth, can strike power lines and antennae and pass through the wires to the terminal equipment such as TV.

If electric current passes through something, it heats up. This is called Joule Heating. Lightning, as Sarah explained, results in huge electrical currents. Because Joule Heating is proportional to the square of the current, then things that have the electrical current passing through them also get hot.

In the case of lightning striking a tree, if the trunk is damp from the sap or the rain, this moisture can boil instantly, causing parts of the tree to blow off explosively. (Which is one of many good reasons not to stand under a tree during a storm!) The electronics and wires in a television can be subjected to the same thing. They might not explode, but they could over heat and burn out.

However, there is another effect. As Sarah also said, there is a high voltage involved. This voltage can be so high that it can cause semiconductors to break down. In fact, that’s how lightning discharges occur… it is the electrical breakdown of air (often triggered by cosmic rays). Anyway, this high voltage can also cause problems for the sensitive microelectronics in a television set.

Lightning is a sudden discharge of high voltage and high current arising between charged clouds. These surges, in their path towards the earth, can strike power lines and antennae and pass through the wires to the terminal equipment such as TV. The huge currents and voltages, even though of short life, can damage the electrical components and electronic circuits which are usually designed for low power. The surges are so powerful that they can destroy the equipment even if they are off but connected to the mains.

Lightning is a sudden discharge of high voltage and high current arising between charged clouds. These surges, in their path towards the earth, can strike power lines and antennae and pass through the wires to the terminal equipment such as TV. The huge currents and voltages, even though of short life, can damage the electrical components and electronic circuits which are usually designed for low power. The surges are so powerful that they can destroy the equipment even if they are off but connected to the mains.