111.
An equation is given as $$\left( {p + \frac{a}{{{V^2}}}} \right) = b\frac{\theta }{V},$$ where $$p =$$ pressure, $$V =$$ volume and $$\theta =$$ absolute temperature. If $$a$$ and $$b$$ are constants, then dimensions of $$a$$ will be
113.
Turpentine oil is flowing through a tube of length $$l$$ and radius $$r.$$ The pressure difference between the two ends of the tube is $$p.$$ The viscosity of oil is given by
$$\eta = \frac{{p\left( {{r^2} - {x^2}} \right)}}{{4vl}}$$
where, $$v$$ is the velocity of oil at distance $$x$$ from the axis of the tube. The dimensions of $$\eta $$ are
115.
When a small sphere moves at low speed through a fluid, the viscous force $$F,$$ opposing the motion is experimentally found to depend upon the radius $$r,$$ the velocity $$v$$ of the sphere and the viscosity $$\eta $$ of the fluid. Expression for force is
We can thus say that the viscous force $$\left( F \right)$$ is the function of radius $$\left( r \right),$$ velocity $$\left( v \right)$$ and viscosity $$\left( \eta \right).$$
$${\text{or}}\,\,F = f\left( {\eta ,r,v} \right)\,\,{\text{or}}\,\,F = k{\eta ^x}{r^y}{v^z}\,......\left( {\text{1}} \right)$$
Where $$k$$ is a constant.
Now, dimensions of the constituents are
$$\eqalign{
& \therefore \left[ {ML{T^{ - 2}}} \right] = {\left[ {M{L^{ - 1}}{T^{ - 1}}} \right]^x}{\left[ L \right]^y}{\left[ {L{T^{ - 1}}} \right]^z} \cr
& = \left[ {{M^x}{L^{ - x + y + z}}{T^{ - x - z}}} \right] \cr} $$
Equating the exponents of similar quantities of both sides we get, $$x = 1; - x + y + z = 1$$ and $$ - x - z = - 2$$
Solving for $$x,y\,\& \,z,$$ we get $$x = y = z = 1$$
Equation (1) becomes $$F = k\eta rv$$
Experimentally, it was found that
$$k = 6\pi \,\,{\text{or}}\,\,F = 6\pi \eta rv,$$ which is the famous Stokes' law.
116.
The value of resistance is $$10.845\,\Omega $$ and the value of current is $$3.23\,A.$$ The potential difference is $$35.02935\,volt.$$ Its value in significant number would be
The significant number in the potential, $$V = iR;$$ should be the minimum of either $$i$$ or $$R.$$ So corresponding to $$i = 3.23\,A,$$ we have only three significant numbers in $$V = 35.02935\,V.$$ Thus the result is $$V = 35.0\,V.$$
117.
Dimensions of ‘resistance’ are same as (where $$h$$ is Planck’s constant and $$e$$ is charge)
118.
In the equation $$P = \frac{{RT}}{{V - b}}{e^{\frac{{aV}}{{RT}}}}$$
$$V = $$ volume, $$P = $$ pressure, $$R = $$ universal gas constant, and $$T = $$ temperature
The dimensional formula of $$a$$ is same as that of
As we know that,
Dimension of $${\varepsilon _0} = \left[ {{M^{ - 1}}{L^{ - 3}}{T^4}{A^2}} \right]$$
Dimension of $$E = \left[ {ML{T^{ - 3}}{A^{ - 1}}} \right]$$
So, dimension of $$\frac{1}{2}{\varepsilon _0}{E^2} = \left[ {{M^{ - 1}}{L^{ - 3}}{T^4}{A^2}} \right] \times {\left[ {ML{T^{ - 3}}{A^{ - 1}}} \right]^2}$$
$$ = \left[ {M{L^{ - 1}}{T^{ - 2}}} \right]$$
120.
A student measured the length of a rod and wrote it as $$3.50 \,cm.$$ Which instrument did he use to measure it?
A
A meter scale.
B
A Vernier calliper where the $$10$$ divisions in Vernier scale matches with $$9$$ division in main scale and main scale has $$10$$ divisions in $$1 \,cm.$$
C
A screw gauge having $$100$$ divisions in the circular scale and pitch as $$1 \,mm.$$
D
A screw gauge having $$50$$ divisions in the circular scale and pitch as $$1 \,mm.$$
Answer :
A Vernier calliper where the $$10$$ divisions in Vernier scale matches with $$9$$ division in main scale and main scale has $$10$$ divisions in $$1 \,cm.$$