There is a ring of radius $r$ having linear charge density $\lambda$ and rotating with a uniform angular velocity $\omega$. The magnitude of the magnetic field produced by this ring at its own centre would be ( $\mu_0=$ permeability of air)
$\frac{\lambda \omega^2}{2-\mu_0}$
$\frac{\mu_0 \lambda^2 \omega}{\sqrt{2}}$
$\frac{\mu_0 \lambda \omega}{2}$
$\frac{\mu_0 \lambda}{2 \omega^2}$
Three vectors $\vec{a}, \vec{b}$ and $\vec{c}$ are such that $|\vec{a}|=1,|\vec{b}|=2$ and $|\vec{c}|=4$ along with $\vec{a}+\vec{b}+\vec{c}=0$ .Then,the value of $4 \vec{a} \cdot \vec{b}+3 \vec{b} \cdot \vec{c}+3 \vec{c} \cdot \vec{a}$ will be
27
-26
-68 problem is wrong.
-34
Two identical metal bars are heated in two different temperatures and allowed to cool in the same surroundings. Which one of the following figures correctly shows their cooling curves?




The inputs to a digital circuit are as shown below. The output Y is

$A+B+\bar{C}$
$(A+B) \bar{C}$
$\bar{A}+\bar{B}+\bar{C}$
$\bar{A}+\bar{B}+C$
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