#negative charge

p-n Junction, Depletion Region and Diode Characteristics

The negative space-charge region in a p-n junction is located on:

**p-n junction formation** diffusion of holes from p to n and electrons from n to p leaves ionized donors positive on n-side and acceptors negative on p-side, forming space-charge depletion region with electric field directed from n to p (positive to negative), barrier potential V_b ≈0.3 V Ge, 0.7 V Si, opposes further diffusion, drift current due to minority carriers swept by field balances diffusion at equilibrium net current zero. Holes diffuse from p-side to n-side, leaving behind immobile negative ionized acceptors on the p-side, forming the negative space-charge region of the depletion l

Ref: NCERT > Physics Book > Electronic Devices > p-n Junction, Depletion Region and Diode Characteristics

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Electric Charge, Quantization and Conservation

What ensures that the electric field lines from a negative charge always terminate on it rather than extend to infinity?

**Fundamental property of charge** includes additivity and quantization, meaning net charge equals algebraic sum of constituents and each is multiple of e. When rod loses charge, electron removal is inferred, and n = q/e gives transferred count. Negative charges attract positive test charges, so field lines, representing the force direction on a positive charge, point inward toward the negative charge. This attraction defines their termination, unlike positive charges where lines extend outward. Substituting values gives Attraction, which matches expected magnitude for this electrostatic confi

Ref: NCERT > Physics Book > Electric Charges and Fields > Electric Charge, Quantization and Conservation

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Electric Charge, Quantization and Conservation

A point charge \( -8 \, \mu\text{C} \) is at the origin. What is the electric field magnitude at a point 4 m along the z

**Fundamental property of charge** includes additivity and quantization, meaning net charge equals algebraic sum of constituents and each is multiple of e. When rod loses charge, electron removal is inferred, and n = q/e gives transferred count. E = (k |q|/r²) . k = 9 × 10⁹ N·m²/C² , q = 8 × 10⁻⁶ C , r = 4 m . E = 9 × 10⁹ × (8 × 10⁻⁶/(4)²) = 9 × 10⁹ × (8 × 10⁻⁶/16) = 4.5 × 10³ N/C . Substituting values gives 4.5 × 10³ N/C, which matches expected magnitude for this electrostatic configuration, confirming Coulomb's and Gauss's principles and charge quantization consistency.

Ref: NCERT > Physics Book > Electric Charges and Fields > Electric Charge, Quantization and Conservation

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Electric Charge, Quantization and Conservation

How many electrons must be added to a neutral body to give it a charge of \( -8 \times 10^{-8} \, \text{C} \)?

**Fundamental property of charge** includes additivity and quantization, meaning net charge equals algebraic sum of constituents and each is multiple of e. When rod loses charge, electron removal is inferred, and n = q/e gives transferred count. q = n e , e = -1.6 × 10⁻¹⁹ C . n = (q/e) = (-8 × 10⁻⁸/-1.6 × 10⁻¹⁹) = 5 × 10¹¹ . Substituting values gives 5 × 10¹¹, which matches expected magnitude for this electrostatic configuration, confirming Coulomb's and Gauss's principles and charge quantization consistency.

Ref: NCERT > Physics Book > Electric Charges and Fields > Electric Charge, Quantization and Conservation

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Plasma Membrane

Which of the following membrane lipids carries a negative charge at physiological pH?

Electric field across membrane influenced anionic phospholipids clustered inner leaflet physiological pH seven point four generating negative surface potential crucial signaling recruitment. Phosphatidylserine headgroup contains phosphate pKa less two carboxyl pKa three amine pKa nine net charge minus one neutral pH despite zwitterionic potential measured zeta minus fifteen millivolts inner leaflet ten to fifteen percent total phospholipid outer almost zero. Approximately PS binds Annexin V calcium dependent detection apoptosis C2 domains PKC synaptotagmin polybasic KRas via electrostatic attr

Ref: Levental & Grzybek, Annu Rev Physiol 2010, Phosphatidylserine anionic negative charge electrostatic signaling and clearance.

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Glycolipid and Phospholipid

Which component is responsible for the negative charge of gangliosides?

Acidic character gangliosides derives sialic acid carboxylate not phosphate sulfate fatty acid groups. N acetylneuraminic acid NANA nine carbon sugar pKa about two point six due alpha keto acid carboxyl fully ionized pH seven point four conferring net negative charge and electrophoretic mobility. Monosialoganglioside GM1 carries one charge disialo GD1a two trisialo GT1b three tetra GT1c four enabling separation DEAE anion exchange thin layer chromatography migration anode toward positive electrode. Charge influences calcium bridging modulation binding extracellular matrix proteins complement f

Ref: Schauer R., Glycoconjugate J 2000, Sialic acid chemistry ganglioside negative charge and functions.

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Titration of Amino Acids

Which of the following amino acids contributes most to a peptide’s negative charge at pH 7?

Aspartic acid is the scientifically accurate answer to this question. Within the study of Titration of Amino Acids, this concept is well-established through extensive research and is documented in standard scientific literature. The specific properties, mechanisms, or characteristics of Aspartic acid directly address what is being asked. Among the other options, Lysine, Arginine, and Histidine do not correctly answer this question because they either refer to different concepts, describe properties of other molecules or processes, or represent common misconceptions about this topic.

Ref: Lehninger Principles of Biochemistry, Nelson & Cox, 8th Ed., Ch. 3

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