A tungsten filament used in a flashlight bulb operates at 0.20 A and 3.0 V. If its resistance at 20°C is 1.5Ω, what is the temperature of the filament when the flashlight is on?

The temperature of the filament when the flashlight is on is 2020 °C.

Explanation:

The resistivity varies linearly with temperature:

  (1)

Where:

T: is the temperature of the filament when the flashlight is on=?

T₀: is the initial temperature = 20 °C

α: is the temperature coefficient of resistance = 0.0045 °C⁻¹ 

R₀: is the resistance at T₀ = 1.5 Ω    

When V = 3.0 V, R is:

By solving equation (1) for T we have:

Therefore, the temperature of the filament when the flashlight is on is 2020 °C.

I hope it helps you!            

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.

see earlier answer