A1.70 m cylindrical rod of diameter 0.550 cm is connected to a power supply that maintains a constant potential difference of 13.0 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 17.1 a. you can ignore any thermal expansion of the rod. 1.find the resistivity and for the material of the rod at 20 ^\circ {\rm c}. (rho= ? ω*m)

2.find the temperature coefficient of resistivity at 20 ^\circ {\rm c} for the material of the rod.(α= ? (c)^-1)

ρ(20°C) = 9.7 * 10^-6 Ω m

α = 0.0013 /°C

Explanation:

Step 1: Data given

length of the rod = 1.70 meters

diameter = 0.55 cm

Potential difference = 13.0 V

Temperature = 20°C →18.7 A

At 92°C → 17.1 A

Step 2: Calculate the resistivity

ρ =  (RA)/L

 ⇒ with R = the resistance of the rod

   ⇒ R = V/I0 = 13/18.7 = 0.695 Ω

 ⇒ with L = length in meters  = 1.70 m

 ⇒ with A = cross sectional area in m^2  =  π * r²  

    ⇒ r = d/2 = 0.550/2 = 0.275 cm = 0.00275m

ρ(20°C) = (R*π * r²  )/L

ρ(20°C) = (0.695 * π 0.00275²)/1.7

ρ(20°C) = 9.7 * 10^-6 Ω m

ρ(92°C) = (R*π * r²  )/L

  ⇒ R = 13/17.1 = 0.76

ρ(92°C) =(0.76 * π 0.00275²)/1.7

ρ(92°C) = 1.06 *10^-5 Ω m

2.Find the temperature coefficient of resistivity at 20 ^\circ {\rm C} for the material of the rod.(α= ? (C)^-

RT = R0*[1 + α(T-T0)]

⇒ with RT = the resistance of the rod at tmperature T = 92.0°C

⇒ with R0= the resistance of the rod at temperature T = 20°C

⇒ with α = the temperature coefficient of resisivity

⇒ with T = 92°C

⇒ with t0 = 20°C

RT = V/I = 13.0/ 17.1 =0.76 Ω

α =((RT/R0)-1)/(T-T0)

α = ((0.76/0.695)-1)/(92-20)

α = 0.0013 /°C

not too sure thinking it will always be directed towards the centre of the earth. could be wrong not sure

quantum mechanics or quantum physics is physics of very small objects (particles) and physical entities.

quantum physics has some parallels to our macro world and some pretty unique ideas which theoretically and mathematically proven to be true even though we will never be able to access them because of our size.

there are many types of particles: subatomic, elementary etc.

subatomic means they are smaller than atom, elementary means they are at the very basis of everything.

subatomic particles are for eg. protons, neutrons but not electrons.

elementary particles are categorised into 3 groups by what they do.

these 3 groups are quarks, leptons and bosons.

light for example is a particle more precisely a photon a part of leptons.

proton (subatomic particle) is made out of 2 up quarks and 1 down quark each of these has a fractional charge like . (i crazy)

most famous scientist who contributed to this physics are:

the topic itself us understand a lot and will probably be vastly used in the future (quantum computers, understanding the big bang,

we also must not forget quantum effects like:

and there is more. but probably too much for this answer to be consistent due to my average understanding of this topic.

hope this you understand quantum mechanics a little more. i'm not an expert in the topic (so don't be like wth if you are an expert) but i'm very interested in it.

anyways quantum physics is a very hard topic (harder than physics (perhaps)) therefore searching for every information there is about it and learning it is unfortunately impossible (you can only specialise into 1 - 3 things or more (perhaps

have fun and i wish you luck!

r3t40