Physics - Online Test

Δl=αlΔT=1.20×10−5×63×18=0.0136cm

final length =63.0136cm

There are three rules on determining how many significant figures are in a number:

• Non-zero digits are always significant.
• Any zeros between two significant digits are significant.
• A final zero or trailing zeros in the decimal portion ONLY are significant.

So keeping these rules in mind, there are 3 significant digit.

if only inductor is present in circuit then R = 0

tanϕ=XLR=XL0=∞

hence, phase angle ϕ=90∘

If the battery has e.m.f E, resitance of the potentiometer is R and the internal resistance of the battery is r, then the current I flowing in the potentiometer wire is given by, 

I=E(R+r)I=2(4+1)I=0.4A

The potential difference V across the potentiometer 

V=I×R⇒V=0.4×4V=1.6V

The potential gradient = ( potential drop across the potentiometer)/ length of the potentiometer wire)

= V/l

= 1.6/1

Potential gradient  = 1.6 V/m

The emf of the cell

Instantaneous speed is the slope of the line at that point.

According to given image 

Slope of line at x​​​​​​2 = 270−04−1.8=2702.2

= 122.7 ≈123