Remember the truth tables for basic logical operations (and, or, not, implication). A contradiction is always false, and a tautology is always true
For \( S_1 : (p \rightarrow q) \land (p \land \sim q) \), the truth table is:
\( p \) | \( q \) | \( p \rightarrow q \) | \( p \land \sim q \) | \( S_1 \) |
---|---|---|---|---|
T | T | T | F | F |
T | F | F | T | F |
F | T | T | F | F |
F | F | T | F | F |
From the truth table, \( S_1 \) is a Contradiction, as \( S_1 \) is always false.
For \( S_2 : (\sim p \land q) \lor (p \land \sim q) \), the truth table is:
\( p \) | \( q \) | \( p \land q \) | \( \sim p \land q \) | \( p \land \sim q \) | \( (\sim p \land q) \lor (p \land \sim q) \) | \( S_2 \) |
---|---|---|---|---|---|---|
T | T | T | F | F | F | F |
T | F | F | F | T | T | T |
F | T | F | T | F | T | T |
F | F | F | F | F | F | F |
From the truth table, \( S_2 \) is a Tautology, as \( S_2 \) is always true.
Hence:
\( S_1 \) is Contradiction, and \( S_2 \) is Tautology.
The value of current \( I \) in the electrical circuit as given below, when the potential at \( A \) is equal to the potential at \( B \), will be _____ A.
Two light beams fall on a transparent material block at point 1 and 2 with angle \( \theta_1 \) and \( \theta_2 \), respectively, as shown in the figure. After refraction, the beams intersect at point 3 which is exactly on the interface at the other end of the block. Given: the distance between 1 and 2, \( d = \frac{4}{3} \) cm and \( \theta_1 = \theta_2 = \cos^{-1} \left( \frac{n_2}{2n_1} \right) \), where \( n_2 \) is the refractive index of the block and \( n_1 \) is the refractive index of the outside medium, then the thickness of the block is …….. cm.