In the bohr model of the hydrogen atom the electron circulates around the nucleus in a path of radius 5.1❌10^-11 meter at a frequency of 6.8❌10^15 rev/sec. what value of magnetic field is set up at the center of the orbit?

Asmall electric heater, immersed in 80g of water in a calorimeter of 40j/k raises the temperature from 10.5 degree celsius to 25 degree celsius in 12 minutes. using the same apparatus with 50g of oil instead of water, it is found that the temperature of oil rises from 7 degree celsius to 27 degree celsius in 10 minutes. find specific heat capacity of the oil.