Class 12th

A wire carrying a current I along the positive $x$ -axis has length $L$ It is kept in a magnetic field $\vec{B}=(2\hat{i}+3\hat{j}-4\hat{k})$  T. The magnitude of the magnetic force acting on the wire is:

A very long conducting wire is bent in a semi-circular shape from $\mathrm{A}$ to $\mathrm{B}$ as shown in figure. The magnetic field at point $\mathrm{P}$  for steady current configuration is given by:

10 resistors, each of resistance $\mathrm{R}$ are connected in series to a battery of emf $\mathrm{E}$ and negligible internal resistance. Then those are connected in parallel to the samebattery, the current is increased $\mathrm{n}$ times. The value of $n$  is:

The resistance of platinum wire at $0^{\circ }\mathrm{C}$ is $2\mathrm{\Omega }$ and $6.8\mathrm{\Omega }$ at ${80}^{\circ }\mathrm{C}$ . The temperature coefficient of resistance of the wire is:

An electric dipole is placed as shown in the figure

The electric potential (in $102\mathrm{V}$ ) at point $\mathrm{P}$ due to the dipole is $\left({?}_0=\right.$ permittivity of free space and $\left.\frac{1}{4\pi {?}_0}=K\right)$  :

A long solenoid of radius 1mm has 100 turns per mm. if 1 A current flows in the solenoid, the magnetic field strength at the centre of the solenoid is:

A biconvex lens has radii of curvature, 20cm each, If the refractive index of the material of the lens is 1.5 , the power of the lens is:

Match List -I with List -II.

List -I
(Products formed)
(a) Cyanohydrin
(b) Acetal
(c) Schiff's base
(d) Oxime

List-II
(Reaction of carbonyl compound with)
(i) NH?OH
(ii) RNH?
(iii) alcohol
(iv) HCN

Choose the correct answer from the options given below:

Match List -I with List -II.

List -I
(Drug class)
(a) Antacids
(b) Antihistamines
(c) Analgesics
(d) Antimicrobials

List-II
(Drug molecule)
(i) Salvarsan
(ii) Morphine
(iii) Cimetidine
(iv) Seldane

Choose the correct answer from the options given below: