Question

a teacher used a Geiger-Muller(GM)tube to measure the background radiation in her laboratory.
she rest the counter to zero,waited one minute and then took the count reading.she then repeated the same procedure two more times.
The results are as follows,
count after one minute-15
-24
-18
The readings here are correct.
Why are the readings different?

Answer 1

It changes because radiation always differs in the atmosphere because of the nuclear plants and of pollution around us. Even though it is indoors.