# Lightning Formula

Lightning is a phenomenon which occurs during a thunderstorm when the air currents rise and the water droplets fall. As a consequence of this process, positive charges build at the cloud’s upper edge, while negative charges accumulate near the cloud’s lower edge and also near the ground. This separation of positive and negative charges results in the creation of lightning. The lightning formula is used to find the distance at which lightning takes place. It depends on the speed of sound in the air and the time gap between thunder and flash.

**Formula**

The lightning formula is given by the product of the speed of sound in air and the amount of time that has passed between the lightning strike and the thunder. It is denoted by the symbol d. Its standard unit of measurement is the same as distance, that is, meters. Its dimensional formula is given by [M^{0}L^{1}T^{0}]. It is also known as the storm distance formula.

d = 343tWhere,

- d is the lightning distance,
- t is the time interval between lightning flash and thunder.

**Derivation**

The lighting formula is derived by using the formula for distance travelled by an object.

Suppose sound travels a distance d with speed s in a time frame of t seconds.

We know that the distance of an object is equal to the product of its speed and time taken. So we have,

d = st ….. (1)

The speed of sound in air is 343 m/s. By substituting the value of s with 343, the formula becomes,

d = 343tThis derives the formula for lighting distance.

**Sample Problems**

**Problem 1: Calculate the lightning distance if the time interval between flash and thunder is 3 s.**

**Solution:**

We have,

t = 3

Using the formula we get,

d = 343t

= 343 (3)

= 1029 m

**Problem 2: Calculate the lightning distance if the time interval between flash and thunder is 10 s.**

**Solution:**

We have,

t = 10

Using the formula we get,

d = 343t

= 343 (10)

= 3430 m

**Problem 3: Calculate the lightning distance if the time interval between flash and thunder is 7 s.**

**Solution:**

We have,

t = 7

Using the formula we get,

d = 343t

= 343 (7)

= 2401 m

**Problem 4: Calculate the lightning distance if the time interval between flash and thunder is 12 s.**

**Solution:**

We have,

t = 12

Using the formula we get,

d = 343t

= 343 (12)

= 4116 m

**Problem 5: Calculate the time interval between flash and thunder if the lightning distance is 1000 m.**

**Solution:**

We have,

d = 1000

Using the formula we get,

d = 343t

=> t = d/343

=> t = 1000/343

=> t = 2.9155 s

**Problem 6: Calculate the time interval between flash and thunder if the lightning distance is 600 m.**

**Solution:**

We have,

s = 343

d = 600

Using the formula we get,

d = 343t

=> t = d/343

=> t = 600/343

=> t = 1.7493 s

**Problem 7: Calculate the time interval between flash and thunder if the lightning distance is 1500 m.**

**Solution:**

We have,

s = 343

d = 1500

Using the formula we get,

d = 343t

=> t = d/343

=> t = 1500/343

=> t = 4.373 s