Explain the difference between the following substances with the help of examples:
(i) Paramagnetic
(ii) Diamagnetic
(iii) Ferromagnetic
i. Paramagnetic Substances
Step 1: Paramagnetic materials have unpaired electrons in their atomic structure, which cause weak attraction to external magnetic fields.
Step 2: They have a small and positive magnetic susceptibility and align weakly with the applied magnetic field. Examples: Aluminum, Platinum, Oxygen. \[ \boxed{\text{Weak attraction, e.g., Aluminum}} \]
ii. Diamagnetic Substances
Step 1: Diamagnetic materials have all paired electrons, causing them to create an induced magnetic field in the opposite direction to the applied field.
Step 2: They have a small and negative magnetic susceptibility and are weakly repelled by the applied magnetic field.
Examples: Copper, Gold, Bismuth. \[ \boxed{\text{Weak repulsion, e.g., Copper}} \]
iii. Ferromagnetic Substances
Step 1: Ferromagnetic materials have domains of atoms that align strongly with an external magnetic field, creating a strong attraction.
Step 2: They have high positive susceptibility and retain magnetization even after removing the external field.
Examples: Iron, Nickel, Cobalt. \[ \boxed{\text{Strong attraction, e.g., Iron}} \]
Focal length of each lens is 10 cm as shown in the given figure. Find the distance of the image of point object O from the convex lens and also draw the ray diagram. If both lenses are placed in contact, what will be the power of the combined lens?
State the required conditions for the interference of light. Find the value of maximum resultant intensity of two waves having intensities \( I \) and \( 4I \), when sources are (i) coherent and (ii) non-coherent.
A monochromatic ray of light is incident at an angle of \( 45^\circ \) on the face AB of a right-angled prism (\( A = 90^\circ \)), as shown in the figure. The emergent ray is refracted tangentially from the face AC. Find out the refractive index of the prism material.
What are Kirchhoff's two laws for the electrical circuit? Find out the reading of the ammeter with the help of the given circuit, while its resistance is negligible.