Two different electrical devices have the same power consumption, but one is meant to be operated on 120-V AC and the other on 240-V AC. What is the ratio of the resistance of 240V device to the resistance of the 120V device i. e. \frac{R_{240}}{R_{120}} R 120 R 240 ?

4

Explanation:

For same Power one device is operated at and another at

Suppose and is the resistance of first and second device respectively

using

For first device

For second Device

Ratio of resistances are

the answer is b ) square root of 5

answer: the correct answer is 1.

explanation: there are various process in which a radioactive nuclei decays:

1) alpha decay: in this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. the mass number is reduced by 4 units.

2) electron capture: in this decay process, a parent nuclei absorbs an electron and gets converted into a neutron. simply, a proton and an electron combines together to form a neutron. mass number does not change in this process.

3) gamma ray emission: it is a decay process in which an unstable nuclei gives excess energy by a spontaneous electromagnetic process. this decay releases . this process does not change the mass number.

4) positron emission: it is a type of decay process, in which a proton gets converted to neutron and an electron neutrino. this is also known as -decay. in this the mass number remains same.

from the above information, we see that only alpha-decay is producing a change in the mass number of the nucleus.