A1.60 m cylindrical rod of diameter 0.550 cm is connected to a power supply that maintains a constant potential difference of 17.0 v across its ends, while an ammeter measures the current through it. you observe that at room temperature (20.0 ∘c) the ammeter reads 18.7 a , while at 92.0 ∘c it reads 17.3 a . you can ignore any thermal expansion of the rod.

part a

find the resistivity and for the material of the rod at 20 ∘c.

part b

find the temperature coefficient of resistivity at 20∘c for the material of the rod.

2) an 18-gauge copper wire (diameter 1.02 mm) carries a current with a current density of 1.90×106 a/m2 . copper has 8.5×1028 free electrons per cubic meter.

part a

calculate the current in the wire.

express your answer using two significant figures.

part b

calculate the drift velocity of electrons in the wire.

express your answer using two significant figures.

1.

Part a)

Part b)

Explanation:

Part a)

Length of the rod is 1.60 m

diameter = 0.550 cm

now if the current in the ammeter is given as

V = 17.0 volts

now we will have

R = 0.91 ohm

now we know that

Part b)

Now at higher temperature we have

R = 0.98 ohm

now we know that

so we will have

2.

Part a)

Part b)

Explanation:

Part a)

As we know that current density is defined as

now we have

Now we have

so we will have

Part b)

now we have

so we have

so we have

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.

does anyone know or what?